Obvious Rule Patch



"That said, you can’t create a focus item that helps you create other focus items. It’s... uh, it’s a magic thing. Just doesn’t work."

- The Dresden Files RPG

Games, of various types, are about rules. They may have intricate backstories, multi-layered plots and other such. But in the end, they're about rules. Rules define what are legal moves and what aren't (even Calvin Ball, which just doesn't have the same rules all the time). Rules create fun.

But sometimes, rules can interact in ways that developers didn't intend. Sometimes this makes the game more fun, but more often than not, it leads to Gameplay Derailment.

So, you're a game developer, and it's two weeks from shipping your next great game. Then one of your testers comes to you with a horrifically game-breaking scenario, a way for a player to game the rules so that their powers spiral out of control and automatically win without a fight. And the rule interaction is very complicated; you can't just tweak a few things to bring this back into balance. In order to truly fix the problem, you would need to rebuild a number of rules, test those rules and so forth... and miss your ship deadline. What do you do?

Or maybe your game is out there already. Thousands, maybe millions of people are playing and enjoying it. Then some Power Gamer figures out how to game the system and auto-win with some horrific combination of moves. You certainly can't "uncreate" the game once it's out there, nor can you radically modify the rules so that particular combo doesn't work, because that would fundamentally change the game and honk off millions of customers. What do you do?

Make an Obvious Rule Patch. That is, create a completely arbitrary rule that forcibly prevents the particular interaction from happening, while having as little effect on other rules as possible. Doesn't matter if it sticks out like a sore thumb even to someone who hasn't played the previous version.

Note that issuing an Obvious Rule Patch for a competitive multiplayer game too soon can damage the evolving Metagame, which can often bring potential Game Breakers back into balance. And just so we're clear, "Obvious Rule Patch" refers to the rule that obviously exists solely to patch up something rather than the something that "obviously" needs a rule patch. "Rule" here is a simple adjective- the Patch is the focus, and the Obviousness is what makes it this trope. For the obviously needed patches, see There Should Be a Law. Sort of.

This sometimes is a result of Executive Meddling - showing once more that despite the negative press it gets, the trope is not always a bad thing.

Compare and contrast Nerf. May, if the situation is enough of a corner case, result in That One Rule.

Board Games

 * The "ko" rule in Go exists purely to prevent infinite loops.
 * Additionally, in Chinese Go, the "superko" rule is there to prevent the rare triple ko, an infinite loop that can still occur in Japanese Go. Nobody's tried to "patch" Eternal Life, an infinite loop that's so rare it's not worth considering.
 * An even better example is the komi rule. Since black moves first, it often begins with sente, where the player makes a series of moves the opponent must defend against. The rule gives white somewhere between a 4.5 and 7.5 point advantage in most tournaments.
 * Examples in Chess:
 * The most recent major rule change in chess was allowing a pawn to move two squares on its first move. It was soon noticed that this allowed a pawn to "slip past" an enemy pawn which would otherwise have been able to capture it. Since the two-square rule was only meant to make the game faster and not to alter strategy, the en passant rule was introduced to patch the hole: if a pawn slips past another like this, the opposing pawn gets one chance to capture it anyway. (The option must be exercised immediately or lost.) Unavoidably, the two-square rule has changed chess, but en passant has helped to limit this.
 * The funny thing is that anyone strategically-minded enough to be changing the rules of chess should have noticed right away that this allowed a pawn to move such that adjacent pawns have no possibility of capturing them.
 * Chess does not out-and-out ban infinite loops like Go, but does declare the game a draw if the same position occurs three times (as long as one player claims it). More complex loops are prevented by the 50-move rule: a game is drawn if 50 moves pass without a pawn being moved or a piece captured (these, being irreversible, are the key signs of progress in a game). "Perpetual check", where a stubborn player exploits the priority of defending one's king to delay the game indefinitely, is also a draw.
 * The 50 move rule was once subjected to a really obvious rule patch. It was discovered that certain positions can be won but require more than fifty moves (without captures or pawn moves) to do so. To take care of this, the rules were changed to list these positions and specifically exclude them from the 50 move rule, allowing players to win the game in such positions instead of drawing. This was abolished in 1992, because it was found that there were far too many of such positions to continue patching the rules like this.
 * Note that the game isn't automatically drawn due to threefold repetition or the fifty-move rule; a player must claim the draw.
 * Chinese chess, Xiangqi, is less forgiving of perpetual checks. If you check five turns in a row without pause, you lose the game. However, in Xiangqi, the general's movement is limited to a small area called the palace, so if you really can't figure out how to checkmate him, you deserve the loss.
 * The castling rules in chess also have an Obvious Rule Patch requiring the king and the rook to be on the same rank, to prevent the one-in-a-million scenario of a never-moved king using vertical castling along the e-file with a pawn promoted to rook.
 * And speaking of pawn promotion, that's another rule which is now specified very carefully to avoid certain abuses—such as remaining a pawn or promoting to an enemy piece. Yes, there are positions where those options are good, although it's vanishingly unlikely that they'd ever occur. See here for an example of when promoting to an enemy piece is more beneficial.
 * There's one story where a student promoted his pawn to a king because his teacher, George Koltanowski, had forgotten to mention this was illegal. George says he responded by checkmating both kings at once.
 * In Shogi, almost all games end in checkmate. However, there's a situation which was not originally thought of where it can be impossible for either side to achieve a checkmate if both kings enter the opposing sides promotion ranks. This is called "entering king," and is regarded as one of the only possibilities for a stalemate. If such a position arises, arbitrary rules on counting the amount of pieces 'owned' by each side and assigning a point value to them were created. If either side has less than 24 points, then they lose. If both sides have enough points, then the game is simply replayed over again with the starting move switched to the other player.
 * Another situation arrived relatively recently in shogi professional matches. The rule used to be that if a player caused a repetition of moves three times in a row, the game would be considered a draw. (This would happen through one player dropping a piece, a sacrifice occurring, and then an endless cycle of sacrificing and replacing the same piece.) However, one shogi professional found that he could avoid this rule by switching the type of piece he played every other move, so that the repetition did not occur three times in a row. Under those rules, there was nothing that could be done and play continued with the same moves being made until the defending player finally got fed up and tried something else, allowing the instigator to go on and win. The rules were hastily changed so that if an exact same board position (including pieces in hand) happens four times, regardless of sequence, then it's an automatic draw. (Note that this is different from perpetual check, which results in an auto-loss for the instigator.)
 * In Japanese Mahjong, players need at least 1 yaku to win a hand. The Tanyao yaku is particularly easy to get with open (containing called discards from other players) hands. This has caused many players to call tiles left and right in order to finish their hand with Tanyao as their only yaku for a pitiful point value, much to the annoyance of any opponents denied a bigger scoring opportunity as a result. This has led to a controversial House Rule known as "kuitan nashi" which only allows Tanyao on closed hands.
 * Another one is the agari yame House Rule. Normally, if the dealer wins a hand, an extra hand is played which does not count towards the total number of hands in the match, and the dealer keeps the dealer button for the extra hand(s). With the agari yame rule in effect, the extra hand is not triggered if the dealer wins on the last hand and they are in first place. This is to prevent a Springtime for Hitler scenario - in the Japanese variant, it is not uncommon for the player who ends in first place to receive a large bonus (of ranking points in league or tournament play, or cash in gambling play). Thus, on the final hand without agari yame, if the dealer is in first place, they might be better off not winning the hand to end the game and secure their first-place finish, while winning the hand would trigger an extra hand, during which they would have to risk being knocked out of first.
 * A game of Scrabble ends when a player runs out of tiles, or when each player takes three straight non-scoring turns and at least one player actually has points. The last clause had to be added because of a strange tournament game where a player accidentally dropped a tile face up in attempting to put tiles on his rack. The opponent noticed that this tile would combine with his own rack to form a word allowing him to reach the edge of the board, and so simply passed. The player who showed the tile, however, wasn't in a hurry to make the first word either, and started by just exchanging some tiles to get a better rack. When he finally did make a play, on the 3rd turn, it was a fake word. The other player still had the opportunity to make the play he was looking for, but opted for something better: challenge the word off the board! As this was the sixth scoreless turn, the game ended immediately, and each player lost points from the value of their tiles. The player who made the challenge was able to see that by doing so, he would automatically win by a score of negative 8 to negative 10.
 * The Finnish board game Afrikan tähti (Star of Africa) had a small flaw in the original rules - the game could become unwinnable for one or more players because of the cost of travelling by sea and the possibility of getting robbed on one of the islands. After 50 years of unwinnable games and House Rules, the sea travel was patched to resolve the formerly unwinnable situations by making sea travel free if the player has no money but only 2 spaces at a time.
 * The Battlestar Galactica board game has had a few. In the base game, the secrecy rules were essentially a patch for the core mechanic, since the game breaks if players are allowed to openly discuss their card plays. The first expansion included replacements for a particular skill card to fix a degenerate human strategy, and an overlay for certain spaces of the board to fix a degenerate Cylon strategy. It also introduced an execution mechanic, which was patched in the next expansion so that it couldn't be used as a cheap loyalty check.

Card Games
"This is not the original intent of Go Up a Level cards, but it is such a munchkinly and vile idea that we like it too much to say no."
 * Forced bets in poker, including blinds, antes, and bring-ins, are designed to ensure that some or all players have a stake in the pot, preventing everyone from folding until they get a really good hand. In Tournament Play, they are raised continually to prevent overly cautious play (this often leads to people winning World Championships with cards they wouldn't play in a low-limit cash game).
 * The "small blind", "big blind", and "dealer button", used in cardrooms, particularly in Texas Hold'em, ensure that the action moves in an orderly manner, as opposed to previous opening rules like "forced bring-in" (the lowest showing card has to open, common in stud games) or "jackpots" (common in draw games, requiring a hand of certain strength, often a pair of jacks, to begin the betting).
 * Most cardrooms have special "house rules" to ensure speedy play and/or ban unethical maneuvers. Among these are:
 * "Cards Speak": A hand does not have to be declared at the showdown to be played (ie, your flush still beats their three of a kind even if you don't know its a flush when you show it down).
 * "Table Stakes": A player cannot be forced out of a pot due to lack of money (extra bets go into a side pot), and a player can't reach into their pocketbook/offer up their Aston Martin keys and/or the deed to the ranch to call a hand.
 * Anti-collusion rules such as: banning cellphones tableside, requiring cards shown to another player to be shown to the rest of the table, and banning languages other than English at the table. The last one often doesn't cover ASL, in order to avoid violating ADA requirements.
 * One of the most obvious examples is Collectible Card Games and their restricted/banned lists.
 * Lists in the Yu-Gi-Oh Card Game started as just the Limited List: normally, you can have up to three of any one card in a deck, but for game balance reasons the Limited List mandates that only one (Limited) or two (Semi-Limited) copies of certain cards can be included in a deck. Before long, players were discovering interesting ways to break the game using card combos the game designers hadn't foreseen, resulting in absurdly powerful decks that could force a win in a single turn (or even the first turn). Thus the Limited List was expanded to include Forbidden Cards, which cannot be included in a deck at all. The list is changed roughly every six months, with cards being both added to and sometimes removed from it.
 * In an interesting take on this, the formerly-Limited card "Twin-Headed Behemoth" was recently knocked down to 3 because of a ruling change: Its effect (which lets it revive itself from the Graveyard at the end of the turn it's destroyed from the field with 1000 ATK and DEF) specifically states it can only be activated "once per duel". It was put at 1 after it was pointed out that multiple copies of the card would make it impossible to keep track of which copy had used its effect and which haven't, meaning anyone could abuse the confusion and reuse the card's effect illegally. Now, though, the card's ruling has changed so that only 1 copy of it owned by a player can activate its effect that duel, period. The rule change was completely arbitrary, only allowing the card to become unlimited without interfering with the reasons it was limited in the first place. A similar case happened with Treeborn Frog, which won't activate if one is already on the field, allowing it to be unlimited.
 * The worst examples of this in Yu-Gi-Oh are Yata-Garasu and the two Envoys. All of the other cards on the Forbidden list are pivotal in combos; these three cards were banned just because they were that broken. Not helping the Envoys' case is a rule known as priority, which allows the player to activate their effects (which can normally only be activated at times when the player could activate a Normal Spell) immediately when they're Summoned, before the opponent has the chance to activate cards that would destroy them.
 * Following the introduction of the Xyz monsters in the game, the OCG and TCG had their priority rulings patched to prevent people from calling priority on Ignition monster effects.
 * Green Baboon, Defender of the Forest, is another monster with an unusual Obvious Rule Patch story; its effect allows you to pay 1000 LP to summon it from your hand or graveyard if a Beast-Type monster you control is destroyed, but too many duelists were exploiting that effect by bringing it out by purposely suiciding their Beasts in battle. As such, Konami arbitrarily decided its effect can't go off, if the Beast monster was destroyed by battle. This significantly weakened the monster's power and caused many duelists to declare They Changed It, Now It Sucks, but there's a twist to the tale; shortly after the ruling was implemented, guess what came out? A new monster, with the exact same stats as the original Baboon (and even named Yellow Baboon, Archer of the Forest), and the ability to summon itself from the hand if a Beast you control is destroyed by battle. Nice way of covering your ass there, Konami...
 * Also, the "Archfiend" cards, an issue resulting from bowdlerization of card names. In the Japanese version, several cards used the word "demon" in their names, and this word was changed into a bunch of different words in the initial American releases: "Demon's Summon" became "Summoned Skull", "Demon's Axe" became "Axe of Despair", and so on. This worked fine until a series of cards that dealt with "demon" cards started to come out, so a ruling had to be issued to declare "Archfiend" as a "special category of card" which included all the cards that had "demon" in the Japanese name. From then on, "demon" would always be translated as "archfiend".
 * With the recent release of Xyz Monsters, there was a brief period where there were very few written rules about how they actually work - one key problem was the fact that the monster used for Xyz Summoning stayed on the field until "detached" by an effect. Fine, but when does "leave the field" effects trigger? Word of God said when detached, and all hell broke loose. Two already powerful cards got so absurdly broken that a copy could easily fetch well over 100 dollars. Konami quickly made an rule change: These cards never trigger their effects because they aren't treated as cards anymore. It's just as weird as it sounds.
 * The DCI banned / restricted lists from Magic: The Gathering, introduced soon after the first major tournaments.
 * The Urza Block is particularly infamous for producing massively overpowered cards and card combinations, to the point that one card Memory Jar was banned before it was even released, after it was realized just a bit too late what could be done with it.
 * Lampshaded in the series' own Unglued and Unhinged expansions, with cards like Look At Me, I'm The DCI!, which featured current Head Designer Mark Rosewater's stick-figure drawing of a blindfolded figure picking what to ban by throwing darts at cards pinned to a dartboard. Other Unglued cards have 'errata' printed on the card.
 * An even clearer example would be the times MTG has had to give cards errata; it is currently not their policy to reword a card for simply being too powerful, but there are quite a few cards that have different wordings due to rules changes, or interactions that literally break the game (as in, "create situations that the rules don't cover"). This was exacerbated with two major rules changes ('96 and '09). Other cards used to often be the subject of errata which prevent them operating the way the card text might imply them to, sometimes again even before the card is released, although this has been phased out over time.
 * The old errata policy allowed cards to be errata'd for power reasons, but this has since been reverted. Overpowered cards are now banned. For example, Time Vault has been errata'd multiple times with various awkward wording to ensure there was no way to easily untap it and gain infinite extra turns. The latest errata, while much simpler than even the original card, makes the card obviously broken in half (and banned almost everywhere).
 * Animate Dead has always worked (generally) functionally as it was originally intended: it enchants a creature and brings it back from the dead, but the creature dies if the Enchantment does (just like the various Necromancy spells from Dungeons and Dragons). However, the exact mechanics of this process, if and how a creature that would otherwise be immune to a Black Enchantment can be affected and targeted by this, etc., have caused Animate Dead to be another nightmare of errata and Magic legalese. There's a reason only 2 other cards like Animate Dead have ever been made, and every other Reanimation spell thereafter are Instants and Sorceries. Damn!
 * Before Time Walk was released, it was phrased "Target opponent loses next turn", which itself needed to be rewritten after people started misinterpreting it as "Game Over, you lose". (It's still massively overpowered though.)
 * The standard Constructed Deck construction rules of today (at least 60 cards, no more than 4 copies of any non-basic card) are a major obvious rules patch. Originally, the only rule was a minimum of 20 cards per player in the game, theoretically allowing for decks that could win on the first turn nearly 100% of the time (assuming somebody willing to hunt down the requisite number of rare cards to make them work).
 * Speaking of Magic, a few powerful creatures (Serra Avatar, Darksteel Colossus, Purity, Dread, Guile, Vigor, Hostility, Progenitus and Kozilek, Butcher of Truth) have an ability that prevents them from going to the graveyard, shuffling them back into the deck instead. While this looks like an advantage, that just hides a darker motive: it prevents players from discarding the creature cards on purpose so that they can revive them using way cheaper Animate Dead spells. (This is not an idle concern, as entire decks are built around this very tactic.)
 * Note that only the Colossus and Proggy actually avoid hitting the graveyard; the other 6 simply don't stay there for very long, meaning that aforementioned shenanigans are still possible, albeit a bit more difficult.
 * Similarly, some creatures have abilities that only trigger "if you cast [the creature] from your hand" to prevent reanimation shenanigans.
 * Taking this even further, the card Phage the Untouchable has an ability that causes you to lose the game if you didn't cast her from your hand. Like the above examples, this is done to prevent "reanimation" exploits. (It should be noted that Phage's other ability is to cause the opponent to lost the game if she manages to lay a finger on him, so ensuring the "Impractical" part of Awesome but Impractical was kind of necessary in her case.)
 * At one point, the Comprehensive Rules contained a line which read "Ignore this rule." This was because the rule no longer existed but Wizards didn't want to change the numbering to close the gap (as it would screw up all references to rule numbers).
 * The introduction of a new "Planeswalker" card type, almost fifteen years after the game's inception, necessitated such a patch; Planeswalkers could be dealt damage, but since they hadn't existed previously, all existing cards that dealt direct damage could only deal it to creatures and/or players, of which planeswalkers were neither. So a special patch rule was added that allowed such cards to redirect their damage from a player to their planeswalker. If Planeswalkers had been present from the beginning, such a thing would never have been necessary.
 * The "M10" major rules overhaul included changes to the combat rules, which would have made the Deathtouch ability almost entirely useless, so, in the M10 rules, Deathtouch got a special rule exempting it from the new combat rules. It has since been further patched to work properly under the new rules.
 * At least by the Special Edition expansion pack, the Star Wars Customizable Card Game came with a separate glossary three times the size of the (already dense) basic rulebook, which was about 50% "errata" fixing Game Breakers. The other half...well, let's just say this was a very involved game.
 * At one point, it was possible to bid to take 14 tricks in Bridge, despite there only being 13 in a hand, if you felt that you would lose less points by failing such a contract than if the opponents won a bid for 13. After the first time that happened in a major competition, the rules were changed almost immediately.
 * In French Tarot, a chelem is a bonus for winning every trick. The deck also contains a special card called excuse, which can never win a trick. Thus if a player has the excuse in his hand, he would normally not be able to complete a chelem. To patch this, if a player has already won all but the last trick and is left with only the excuse, it will win the trick regardless, completing the chelem. However, this is not enough: there is another bonus for taking the last trick with the smallest trump (number 1), so the player with both the excuse and the trump 1 would be unable to get that bonus while making a chelem. So in this case, winning the second to last trick with the trump 1 also awards the bonus.
 * World Of Warcraft TCG's rulebook should be called "exception book", really.
 * One of the most blatant in cards rather than errata is "Writ of Accountability" from the Star Trek Customizable Card Game, which is essentially a list of Game Breakers followed by "you lose." That is not an exaggeration; the consequence is literally an automatic loss for anyone who's pursued one of a number of strategies.
 * The FAQ on the Munchkin website is full of stuff like "No, thieves can not steal during combat or backstab themselves". This may be viewed as Hypocritical Humor since the term "Munchkin" refers to someone eking out every possible advantage they can from any game mechanic.
 * They're willing to go along with a sufficiently devious rules abuse, though. One famous example is playing Go Up A Level cards on other players; since some monsters will allow players to run away for free if they're below a certain base level, this could be used to force a player to fight that (often quite powerful) monster. The company's response:


 * One card allowed you to change one die roll to be any number that you wanted it to be. However, they didn't specify that it had to be a number between 1 and 6. This led to people declaring that the die roll was one million or negative twelve or whatever, with bizarre results. They later changed the card.
 * Originally, the Wizard class could "charm" a monster by discarding their whole hand. Munchkin players being what they are, they immediately began "discarding their whole hands" when they had nothing in them. Later editions specify a minimum of three cards.
 * The Dragonball Z CCG used the show's Power Levels as a gameplay element, with two characters' current power levels compared on a chart during attacks, and damage dealt accordingly. However, because the numbers for the power levels stayed relatively accurate to the show (wherein, by the end of the series, characters had to go out of their way to not blow up the Earth during their battles), the chart used had to be updated constantly. Still, eventually it became obvious that some characters (especially from early sets) were flat out useless in physical combat even against common cards in later sets, so the chart was eventually abandoned and replaced with a calculation system that didn't particularly make much more sense, but at least kept the game more interesting.
 * In the early days of the Pokémon Trading Card Game, there was a loophole where a deck that contains no Basic Pokémon would prevent the game from ever starting. This is because each player must play down a Basic Pokémon in order to start the game. Thus, when Nintendo bought the card game back from Wizards of the Coast (who wasn't taking it seriously to begin with), Nintendo created a rule for all competitions, regardless of purpose: All decks must contain at least 1 Basic Pokémon.
 * Later on, Fossil Cards, which are a different class of cards that can be played on the field like Basic Pokémon, count as a Knocked Out Pokémon when their Hit Points are depleted. Previously, they were simply discarded with no other penalty. This was because Fossil cards were rarely used for their intended purpose, which was to evolve them into usable Pokémon. Instead, they were treated as walls while the players charged up their Pokémon from the (normally) unattackable Bench. When the Diamond and Pearl sets came out, there were now six different Fossil Cards: Dome Fossil, Helix Fossil, Claw Fossil, Root Fossil, Skull Fossil, and Shield Fossil, plus Old Amber, which has the same traits but isn't a Fossil Card. A player could conceivably put 4 of each into a deck and litter his or her playing field with them, stalling out every match.
 * Note that each of these new rules only indirectly block these loopholes. It seems Nintendo tries its very hardest not to ban anything or to directly address exploits.
 * One from the game's early days was the "Mewtwo Mulligan Deck" - a deck that simply had one copy of the original Mewtwo card and Psychic energy filling out the other 59 cards. Starting a hand without a Basic Pokemon (only a 1/60 chance) allowed the user to declare a mulligan, allowing them to draw another seven cards, and forced the other player to draw another card. This would keep going until the MMD user could either force a loss by running the other player out of draws before the game even began, or got their Mewtwo out and could use its power (to become immune to all damage) to stall the opponent out. A patch was put in to make the extra draw for the opposing player optional.
 * In the trick-taking game Chronicle, wild cards have no suit and no value. There are six wild cards in the deck. Three of them are auto-win cards (the Demon beats everything but the King, the King beats everything, and the Dragon destroys the trick entirely) and three of them have effects unrelated to the trick (the Angel, Sage and Fool). So in theory, in a three-player game the players could play these three cards, resulting in the trick having no winner. The rules specify that the first player wins should this ever actually occur.

Game Shows

 * The Bonus Round on Chain Reaction offered a $10,000 top prize for guessing nine words which were described one word at a time. Initially, the score would light up the one for the first word, then half of each zero for the second through ninth words. After the first week of this rule, where $100 was the highest bonus round win, the scoring format was changed.
 * The Hollywood Squares was mostly a simple tic-tac-toe game involving celebrities. Unlike tic-tac-toe, in the case of a "cat's game" where nobody can get three in a row, a contestant has to get the correct answer to claim the final square, and (unlike with other squares) can't claim it by means of the opponent getting the wrong answer. This led to a Funny Moment in 1999 where, with only one square (Gilbert Gottfried) unclaimed, the contestants went through nine questions before one was finally answered correctly, with the panelists shouting "You Fool!" at every wrong answer as a Running Gag.
 * On Jeopardy!, contestants phrasing a question incorrectly (e.g., "What is Abraham Lincoln?") would be asked by Fleming to use the proper phrasing; following several instances in which contestants just could not get the proper prefix out, the rules were slightly altered to give credit for a correct response so long as it was phrased in the form of a question.
 * The original Fleming era let all contestants keep of all of their winnings. When the show was brought back in 1984 with Alex Trebek, this was changed so that only the winner kept their score. Second and third place initially received parting gifts, but since 2001 were given $2,000 and $1,000 respectively. The reason for this change was that some contestants on the Fleming era would stop playing if they thought they won enough money, or if another contestant built a significant lead. By offering full winnings only to first place, there's more incentive to strive for a win.
 * Password Plus briefly disallowed the use of antonyms in describing the password. After it was discovered that some words just can't be described with a one-word clue that isn't an antonym, this rule was reverted.
 * On The $10,000 Pyramid, in the event of a tie, the teams would originally play another regular, seven-word round to break the tie until one team outscored the other. After an incident where both teams managed three consecutive 7-for-7 tiebreaker rounds, the rules were changed so that whichever team completed the tiebreaker round faster won. Even this rule proved imperfect on one instance on The $25,000 Pyramid (the 1980s revival), where both teams managed to complete their tiebreaker rounds in the full 30 seconds, getting the last word on the buzzer both times.
 * Wheel of Fortune has a few:
 * From 1973-75, contestants could buy a vowel for $250 by landing on the Buy A Vowel wedge...and possibly even without having $250, as one eyewitness reported seeing a negative score...and possibly without having to land on the wedge (recollections are contradictory). There was also the problem of it becoming Lose A Turn if all vowels in the puzzle had been bought. Sometime in 1975 (recollections are very contradictory, spanning from "the first few shows" to "the hour-long stint in December"), the wedge was finally kicked out.
 * This also showed up in the current Bonus Round. First introduced by December 18, 1981, the player originally had to pick five consonants and a vowel to aid in solving. After seven years in which nearly everyone picked some permutation of R-S-T-L-N-E, this changed on October 3, 1988 to provide those letters automatically followed by another three-and-a-vowel from the contestant.
 * Yet another obvious patch was renaming the "On the Menu" category to "Food & Drink". Previously, foods that weren't necessarily available on menus were shoehorned into the category (most egregiously the bonus puzzle BIG GULP), while others were just categorized as "Thing" or "Around the House".
 * The Price Is Right has had a few examples of this:
 * For the first few weeks after the introduction of the Big Wheel (to determine who proceeds to the Showcases), there was no rule about how far it had to be spun. The current rule (at least one complete revolution) was instituted by the end of November 1975.
 * They've also tried several tricks to make Clock Game compatible with four-digit prices, so that saying the thousands digits doesn't eat up precious time. In the 1980s, they tried spotting the thousands digit, but that proved too confusing. Prizes of over $1,000 started showing up again in 2008, but after six months in which they proved pretty much unwinnable, it was decided that the contestant should bid only on a portion of the four-digit prize (e.g., if the prize is a TV and a Blu-Ray player, the player bids on just the Blu-Ray player but wins both for giving the right price).

Tabletop Games

 * This is common in logical puzzles placed in RPGs. You want perfect glue and indestructible rope and disintegration runes so that the players can figure out a clever solution to your logical puzzle - but you don't want them to use those items on anything other than that puzzle. The cheap solution is to make them work only in a specific place, or on specific objects, or only once.
 * In the most recent version of the Tomb of Horrors, the scepter and crown of disintegration (put the crown on your head, touch one end of the scepter to it, you disintegrate) cannot be removed from the room they're in by any means (the description goes to great lengths to cover any eventuality). Earlier versions of the Tomb had no such rule at all. The reason eventually emerged during a conversation on a message board: One of the artists working on an earlier copy of the module was invited to a session of the Tomb DMed by none other than Gary Gygax himself. The artist took the scepter and crown from the room, then eventually placed the crown on the  of Acererak and touched the scepter to it, disintegrating the lich instantly. Gygax was stunned, as the eventuality had never occurred to him. The artist, on the other hand, thought that's what they were there for. The artist was quite surprised when he was later informed of the rule change.
 * Dungeons and Dragons consists of many layers of those. Sometimes applied cyclically, since 3.0 dropped many changes made in AD&D2 and its refinements, most of which were fixes for specific problems... and not all of those problems were rendered moot by 3.0 changes, so they had to be fixed again.
 * Pretty much all of the spell entries more complicated than "You do X damage to Y targets at Z range" in the 3.5 edition rules of Dungeons and Dragons consist of long strings of Obvious Rule Patches.
 * There are spells like Polymorph that are one paragraph of explaining what the spell does, and roughly eleven paragraphs of explaining what the spell cannot do.
 * One of the most basic Obvious Rule Patch is the rule that bonuses of the same types don't stack - only the largest one takes effect (with the exception of dodge bonuses to AC in third edition). This has led to many rule patching to give untyped bonuses types so they couldn't be so easily stacked.
 * 3.0 spellcasters had a bad habit of using summoning heavy creatures in midair, causing them to deal obscene damage as falling objects when they hit opponents. Wizards of the Coast amended the summon spells in 3.5 to prevent creatures from being summoned into an environment that can't support them (i.e., no flying whales).
 * You can't sunder armor in 3.5. You can break weapons, shields, even items they're wearing like pendants. Just not armor. It would be easier to just break the fallen paladin's armor and then stab him, leading to silly situations such as the above.
 * Another patch was the spell Dimensional Door. In 3.5E its pretty much an early teleport spell, in previous editions (as the name implies) it created a pair of portals through which the PCs could travel great distances. While that may not sound so bad, PCs often created horizontal or diagonal doors to bissect enemies (or fortifications!) that lead to instant kills. Another tactic was to open a portal into a volcano or sea and use the exit portal to flood an enemy base with lava or drown it completely.
 * In most D&D-like games, you can't wear more than one or two magical items of a certain "slot" and benefit from all their powers. While it makes sense that you can't wear multiple pairs of, say, boots, there's no reason for the usual "two rings, one amulet" rule other than balance issues. This is usually justified with a contrived excuse that the magic items will interfere with each other. Even though you can often wear a helmet, armor, and a neck slot item, or gloves, bracers, possibly armor (which probably has gauntlets of some sort included), and a ring.
 * In the Fourth Edition, shields count as taking up the magic items arms slot and a wielding-in-hand slot. It means you can't use bracers+shield or two shields and get the magical effects of both.
 * Fourth Edition Dungeons and Dragons errata has had some obvious rule patches: The Ranger ability that let you make continual attacks until you miss was errated to have a 5 attack limit as it was possible to make a build which had an almost zero chance of ever missing, even against the strongest monster in the Monster Manual.
 * Pathfinder is basically a tweaked Dungeons and Dragons 3.5 and (to make up for an initial lack of content) was said to be compatible with 3.5 which lead to some game breakers. They tend to fix these by introducing their own version of the feat/skill/class ability/prestige class. Especially noticeable with spells. The Irresistable Dance spell used to be a no save incapacitation spell. Now, it allows a save though even those who make it have to dance uncontrollably for one round.
 * The Quick Draw feat allows you to draw any item from your pack as a free action... except flasks of alchemist's fire or acid. You also cannot sneak attack with such items, unlike all other weapons. These changes were obviously put in place due to volleys of flasks being popular among 3.5e rogues as a means to fight enemies resistant to physical damage or vulnerable to fire.
 * Construction rules in BattleTech often have restrictions that often seem arbitrary. For example, Protomechs (not-so Humongous Mecha) cannot mount Plasma Cannons. This seems to make no sense, as, being only three tons, they seem like perfect weapons to mount on one. Then you think about just how badly five Plasma Cannons would roast any given Battlemech in a single turn.
 * There was also an instance where Battle Armor riding on an Omni Mech can be shot off of the 'mech by shots that land on the torso. Doesn't seem too bad, but given that there is no weight penalty for carrying Battle Armor, the Battle Armor were always the first to take hits, and the 'mech's torso wouldn't begin to take damage until all the Battle Armor were shot off... it's understandable why the next rulebook created fixed locations for each Battle Armor.
 * Warhammer 40000: A Commissar (of any rank) will never execute himself.
 * "Under no circumstances can any [necron] make more than one teleport move in a single turn... There are no exceptions to this, no matter how clever your logic."
 * "Please note that it is not possible to master-craft grenades!"
 * Space Marine drop pods are clearly 10-man craft (visible in the model and still stated in some codexes), but other codexes expanded it to 12 to allow an independent character to deploy with the squad. Without changing the model.
 * In GURPS, it is possible to enchant a pair of permanent Gate spells and then arrange them to create a perpetual motion machine using electromagnetic principles that could then be tapped for an unending mana supply. (Click the link in the subtopic below if you're curious as to technical details.) However, due to the various components required, this would need a setting where both modern science existed, magic existed, and the Draw Power spell from GURPS Grimoire 3e specifically existed. In the one GURPS setting where this is canonical (GURPS Technomancer), three guesses which spell has an entire sidebar devoted to explaining how it specifically does not exist. Hint: Four-letter word, begins with "G".
 * This probably had something to do with the fact that David R. Pulver, the writer of Technomancer participated/lurked in a Usenet thread where the "Infinite Mana Well" construct was first proposed... at the exact same time Technomancer was in final playtest.
 * In The Trillion Credit Challenge (using Traveller), contestants had to purchase and field a fleet of ships to do battle with other fleets. Doug Lenat fed the parameters of the tournament into a computer (in 1981) which suggested that instead of sending in a balanced fleet of carriers, battleships, cruisers, and so on, he should instead build thousands of tiny patrol boats. He won in a rout - though he took incredible losses, he overwhelmed his opponents through sheer numbers. The organizers then made their first Obvious Rule Patch - they added 'fleet agility' (which could be reduced by several things, most importantly by having damaged ships trying to keep up with undamaged ones) as a parameter for the following year's tournament. When Lenat entered again, his computer used much the same strategy with one change - whenever any of his ships was damaged, they would self-destruct, which kept the average mobility of the fleet up. The organizers then made their second patch - tell Lenat that it was weird to have his unorthodox plans keep winning (since, after all, they relied on ordering millions of men to knowing suicide) and say that if he continued to enter, they would stop holding the tournament. Lenat then bowed out gracefully.
 * The rules for creating abominations in old World Of Darkness. Briefly: if you attempt to turn a werewolf into a vampire, the werewolf gets a skill roll. He wins, he dies peacefully. He loses, he dies horribly but his soul is free. He botches, he becomes an abomination, essentially a walking Game Breaker balanced out by crippling depression. Since there are all sorts of abilities in tWoD that can cause a skill roll to fail or critically fail, the editors in Revised Edition state that nothing short of divine intervention can affect the roll.
 * More recent releases of Arkham Horror, as well as later versions of the rulebook included with some expansions explicitly and seemingly arbitrarily ban certain types of cards from being the initial draw—because the effects of those types can easily render the game unwinnable, typically by making the preparation necessary to actually be able to accomplish much in the game difficult or impossible.

Video Games

 * In an early version of Neverwinter Nights, a loophole in the rules was found that let monks wear a shield in their offhand, making them virtually unhittable for no real downside. In the very next patch, monks were made unable to wear shields and retain monk dodge / attack bonuses at the same time.
 * In an early release of Battlefield 2142, it was entirely possible for two soldiers with nothing better to do to destroy their own Titan (and thus force their team to lose the round) by forcing a transport through the floor of the hangar bay and into the Core.
 * EVE Online has had several updates that were borderline Obvious Rule Patches. However, the patch that prevented carriers from transporting loaded cargo ships was a glaringly Obvious Rules Patch.
 * Similarly, nowadays graviton harmonics prevent players from taking a 3000m^3 cargo container that holds 3300m^3 of cargo... and putting another 3000m^3 container that holds 3300m^3 inside it leaving 300m^3 of free space. With enough cargo containers you could once haul an entire solar system's worth of ore in a single, moderately sized and priced ship.
 * A fairly obscure item from World of Warcraft called the Luffa would remove any bleed effect. A boss over 20 levels later would put a hefty bleed dot on raid members at fairly regular intervals. Everyone would equip their Luffa and make Moroes a total joke. The next patch put a spell level cap on the Luffa ie. you couldn't remove bleed effects over level 60 anymore.
 * Then there's the infamous Corrupted Blood incident from the release of the Zul'Gurub dungeon, which gained enough notoriety to be mentioned in major news media as an example of how populations reacted to the spread of communicable disease. In a nutshell, an exploit of a boss encounter allowed a pet who acquired the debuff to be dismissed and then resummoned in a populated area, instantly spreading it to everyone in the vicinity and decimating entire cities as a result. It was patched several days later so the debuff could not exist outside of the dungeon.
 * An old patch for WoW allowed everyone in a group to place marks - graphical icons that go above monsters or players and are used to make them more visible or indicate a kill order for the group - instead of only the group's leader being able to do it. There followed an unofficial addon while allowed players to automatically strobe the marks across the group members, rapidly swapping them around, much to the annoyance of many players. The very next patch added a notification of who was setting marks.
 * Two patches were done within hours of release. One patch screwed up and gave Warriors extra talent points. Another one was a dupe bug. (Very annoying and difficult to pull off, but mentioning a dupe bug for a ticket gets a very quick response and led to a patch within an hour).
 * In July 2009, a hunter was discovered with a worgen (a sentient, werewolf-like creature) for a pet, and within a few hours the hunter community had figured out how and where to get this particular beast; pretty much everyone who could obtain one had one. Within two days the tamed worgen were patched to have all their skills and attacks completely removed, and after a few more days they were replaced entirely by ordinary white wolves. However, considering that worgen became a playable race in the Cataclysm expansion, this may have been for the better.
 * There was a video posted on YouTube a few years back where a paladin killed, in one move, a raid boss designed for dozens of players to take several minutes to bring down. The Reckoning talent had the effect that when a paladin was struck they might gain a stack of Reckoning, causing their next attack to hit twice. One enterprising player dueled a rogue many times without ever striking back, then went up to the boss in question and proceeded to hit it more than a thousand times in one blow. Within twenty four hours the talent was nerfed so that it caused you to hit twice for the next few attacks. Of course, seeing as Reckoning was about the only ability in the entire game that possessed neither stack limit nor duration, this was only to be expected.
 * In Defense of the Ancients, the Batrider hero has a skill, "Sticky Napalm", that amplifies damage from the Batrider on its victims. Players took advantage of this by building the constant DPS aura item Radiance, which turned Batrider into a real damage-dealer. Apparently Icefrog disagreed, as he proceeded to change Sticky Napalm so that Radiance could not (normally) trigger the bonus damage any more.
 * DotA also has an item called "Kelen's Dagger" that allows teleportation of one's own hero. So, it's even possible to teleport yourself into terrain that you cannot escape from, except by using Kelen's Dagger again once the cooldown ends. Two heroes are forbidden from using Kelen's at all. One of them has an ability to swap positions with another hero, and the other who can hook a hero and reel them in to be right next to him. Either of them could trap an enemy hero (or even a friend, if they were traitorous) into a small patch of terrain that said hero might be stuck in for the entire game, unless the other hero happened to also have bought the Dagger.
 * Starting in version 1.3, Iji tells you in some places (the arena for comes to mind) that "there's no need to fire your Nanogun here". Sometimes it was literally true, but in many cases it was because firing your Nanogun there could bug out the game.
 * Iji has a few things like this in the later versions. When it became possible to win the game without killing anyone, this necessitated the player not fighting one of the bosses, because the only way to get by . The solution?
 * In a later update, it doesn't count as a kill if you reflect an enemy's fire back into them with a force field weapon. Previously, "pacifist" players would gather dropped power-ups by stocking up on health, moving right next to enemies, and catching rockets with the main character's face for the Splash Damage.
 * Kingdom of Loathing automatically ends combat with a special message after 30 rounds of combat (or 50 rounds for some bosses) have elapsed with no winner, with a net result equivalent to successfully running away on the 31st round. This was apparently done originally to prevent a possible near-infinite loop that would result if the player's Muscle was too low to hit the monster and his/her Moxie was too high for the monster to hit him/her, while his/her combat initiative was too low to run away. Newer mechanics make such a situation much less plausible, but the rule has remained and still serves to cap the potential effectiveness of any strategy that involves stalling and drawing out combat for per-round effects. For example:
 * The Ninja Pirate Zombie Robot familiar used to randomly give Meat with a fixed chance of about 1 in 9 per round of combat. Since this made it advantageous to drag out combat to as close to 30 turns as possible without going over and thus using up much more server resources than normal, the NPZR now only gives Meat in the first 10 turns of combat.
 * Another much-maligned Obvious Rule Patch came with NS13: Before NS13, players found that increasing monster level (which also increased XP gains) and increasing noncombat encounter chance were both extremely useful. So when NS13 rolled out, the devs added a rule that made increased monster level cancel out increased noncombat chance. Unfortunately, this had the side effect of making monster level increasers less than useless. Over a year and a half later, the devs realized that nobody liked this in the slightest and removed the rule.
 * Another rule is "can't use Double Fisted Skull Smashing to wield a Chefstaff in your offhand." Due to the way DFSS (halves the power of offhand weapons but leaves enchantments alone) and Chefstaves (lowest power possible but incredible enchantments) work, this rule prevents two builds, a rather unpleasant one and a horribly broken one: the former, a weapon/chefstaff combo that makes a Magic Knight with no detriment for either one, the latter, a Chefstaff/Chefstaff combo that results in spells so powerful that it can take down anything almost in one hit.
 * The KoL staff's usual modus operandi in the event of players accomplishing things they didn't count on players accomplishing is to reward the player for their cleverness/tenacity, then change the game so that the stunt can't be repeated.
 * In the Programming Game RoboWar, allowing robots to teleport and fire weapons interchangeably in the same chronon let a robot with sufficient processor speed leap a considerable distance (depending on its current energy) to put a lethal contact shot into another robot, leaving it next to no time to defend or counterattack—and executing another move after the shot (the "jerker" strategy) made it harder to target for a counterattack. That the robot's energy would already go deeply negative in the middle of the chronon didn't matter much (so long as it didn't fall below -200), since it wouldn't become immobilized by having negative energy until the next chronon. This allowed the "dasher" strategy to achieve considerable dominance, and in time most top-placing robots in tournaments, dashers or not, had to use "anti-dasher" techniques. To rebalance the game, an Obvious Rule Patch was instated (amid much controversy) to prevent move/shoot in the same chronon.
 * Fire Emblem: Rekka no Ken had the absurdly broken Luna spell, which has a damage base of 0 but negates enemy resistance to magic when calculating damage, and has a very good base critical rate. For most of the game, enemies have low resistance anyway, and Luna falls somewhere between okay and kind of bad. However, in the last levels of the game, bosses start to have crazy amounts of resistance to counterbalance your ever-strengthening party. The Luna spell, however, just ignores this and allows Canas (who is arguably a broken character to begin with) to completely annihilate the later bosses in just a few attacks. It even makes it entirely possible for Canas to defeat the final boss with just two hits.
 * It gets nerfed to hell in Fire Emblem: The Sacred Stones, where its hit rate is barely half what it once was, is critical rate IS half what it was, and it has less uses. It's made extremely obvious because there wasn't a single change to any other spell.
 * There's also the Silencer skill in Fire Emblem: Rekka no Ken and The Sacred Stones, which gives your Assassin the chance to instantly-kill any foe, so long as they have a chance to land a critical hit. This allowed them to plow through most bosses with ease. While this was negated by the final bosses of both games, whose equipment automatically reduced the enemy's crit chance to 0, it still left most other bosses vulnerable. It was obviously fixed in Path of Radiance and Radiant Dawn, where the description of the Silencer skill simply states it doesn't work on bosses without any reasoning or attempt at justification.
 * In the MMORPG Lords of Legend, your level bonus is apparently capped at 5 times the number of troops. Few know about the cap, because in order to get even close to the cap, you have to spend weeks doing the exact opposite of what you are supposed to.
 * It is also played straight with the 'invisibility' strategy (You don't show up on attack pages if you haven't won an attack yet), which has been severely nerfed with increasingly harsh and arbitrary restrictions on invisible players.
 * Gaia Online has had quite a few:
 * First, there's soulbinding, the most famous and controversial of the lot. In the first couple months of open beta, users were allowed to buy and sell their rings. This caused a few problems. The most obvious, of course, was that people could buy their way through the game, resulting in many CL 10s who had no idea what they were doing. Another effect was on the economy. Charge Orbs, the items that power up rings, were earned in-game, not bought. Higher-level rings are naturally more valued than weak ones, so people were charging up rings and then selling them, effectively creating expensive items with little to no cost to the users. This was quickly changed so that rings were "soulbound", meaning they could no longer be put on the marketplace.
 * But only rings acquired after the update or older rings that are equipped. Unsoulbound rings are still being sold, and there is also a new ring sold for real money as a Valentine's Day event item. It has officially been described as being permanently unsoulbound.
 * A bit later, CL caps were placed on boss lairs so that people couldn't recruit their CL 10 friends to help them beat the boss. Clever players soon found a way to circumvent this by wearing low-level rings when entering the boss area, then switching out to their stronger ones. The devs soon closed this loophole.
 * In Civilization III, players could initially chop down and replant forests in relatively short order. This made a certain amount of sense, up to a point anyway, but it also created an infinite supply of construction materials. It was quickly patched so that replanted forests contained no useful wood.
 * In Half Life: Episode One when Gordon, any use of it causes all other weapons to vaporize, just like the previous game. The problem is, Alyx is also with you and can kill enemies, causing them to drop their weapons. When they do, the weapons still vaporize for pretty much no reason, almost as if they only held together because a Combine soldier was holding it.
 * In Final Fantasy XI, you gain tactical points (TP) each time you hit an enemy, the amount varying based on the delay of your weapon (higher = more TP per hit). You have to have at least 100% TP (of a 300% cap) in order to perform a weapon skill. This sounds reasonable, except very early on, weapon skills that hit multiple times gave full TP return per hit, leading to being able to perform these weapon skills back-to-back with no need to accumulate TP in the mean time assuming you used a special type of otherwise useless weapon with almost no damage rating and max delay. Square Enix patched this very quickly so that only the first hit (first two when you're dual-wielding) give full TP, and subsequent hits only give 1%.
 * Don't forget Absolute Virtue, who is for all intents and purposes totally invincible due to his ability to use the most powerful abilities of every job, as well as cast high-level black magic that players don't even have access to instantaneously and frequently, wiping out alliances of players in seconds. Every time a method is discovered to defeat him, Square-Enix will immediately squash it by giving Absolute Virtue new resistances and powers as his flaws were discovered.
 * When players killed him by attacking him from areas he couldn't fight back, the developers gave him the ability to draw players to him if they got too far away.
 * Later on, the devs were pressured into rethinking the absurd difficulty of some of their bosses after some bad publicity involving an 18-hour-long fight against a different monster, so they lowered the HP of both that boss and Absolute Virtue and forced them to despawn if not defeated within two hours. Players discovered that a legion of Dark Knights using a combination of the job ability Souleater (consumes HP to increase damage dealt) and Blood Weapon (restores HP equal to melee damage inflicted), he could be bumrushed into defeat. Within days, a patch was made that gave Absolute Virtue (and ONLY Absolute Virtue - other monsters that had previously been defeated with this method were totally untouched) increasing resistance to Souleater damage, making it useless.
 * A theoretical method of defeating him involved using the Scholar's Helix line of spells, which deal a fairly large amount of damage over time. The helix was placed on the enemy, and then a group of Scholars simultaneously use a job ability that doubles the damage dealt by the next tic of damage while halving its overall duration. The result is that most enemies in the game will drop dead immediately, although execution requires very precise timing (and, in most cases, botting). As soon as people discussed how it could be used to defeat Absolute Virtue, "certain notorious monsters" were given a resistance to the use of the JA. Guess who was at the top of the priority list?
 * Pokémon had constant problems with the pokemon Wobbuffet. It's supposed to be a pokemon that cannot directly attack but is streamlined to take advantage of damage reflecting attacks, but instead of being forced to attack, an opponent can just simply switch out his current pokemon over and over until Wobbuffet runs out of PP. To prevent that, in Generation III Wobbuffet and its newly introduced pre-evolution Wynaut were both equipped with the Shadow Tag ability, which prevents the opponent from switching Pokémon in a battle against Wobbuffet/Wynaut until they were either recalled or knocked out or if the foe has some other trap-cancel ability that allows them to flee. Fair enough, except for in a competitive battle where both you and your opponents have Wobbuffet (or the much-less-common Wynaut) who are both equipped with Leftovers and facing each other. You can't fight back because Wobbuffet and Wynaut are only able to counter attacks, not dish them out. Their Shadow Tag abilities will also prevent either of them from switching out, and even if the two were to wear themselves down enough to use Struggle (the only move Wynaut/Wobbuffet knows that deals damage), Leftovers would cancel out what horrendously low damage their moves do, resulting in a draw by eliminating any chance that either of the two will faint. From Diamond and Pearl onwards, Shadow Tag was changed so that any Pokémon who has the Shadow Tag ability who is locked into battle with a foe who also has said ability can negate the effect and switch out without problems. Also, Struggle now always takes away 25 percent of the user's maximum hit points, not 25 percent of the hit point damage the user did to the other guy, so that even if two trainers wound up with Wobbuffet as each person's last Pokémon, once Struggling began the match would end in 5 turns or less (because the 25 percent rounds down, someone with an HP amount that can be divided by 4 with a remainder of 1 could last 1 more turn).
 * Now in the new generation of games, (the fifth) there was a glitch involving the new move Sky Drop. The move makes one Pokemon take another into the air (and then drop it for damage), and when a Pokemon is in the air, it cannot move or be hit (except by a few moves, like Thunderbolt). There was previously a move called Gravity which made Flying-types or levatating Pokemon comes to the ground (this meaning they can be hit by Ground-type moves), and also makes Pokemon in the air come to the ground. So in a double battle, if one of your Pokemon uses Sky Drop and the other then uses gravity, both your & the opponents Pokemon will come to the ground... except while your pokemon can move, theirs is treated as being in the air and cannot move, at all, until they are fainted by a move like, say, Thunderbolt. The Obvious Rule Patch? Nintendo banned the move in Random online battles.
 * The fifth generation games also give us a minor one involving Dream World Pokemon. Almost every Pokemon encountered in the Dream World will have an ability not normally accessible in the main game. This also came with a new breeding mechanic where these abilities could only by passed to offspring if the Pokemon with the ability is female. Starter Pokemon and Eevee's evolutions encountered in the Dream World can never be female, meaning they can have their Hidden Ability or egg moves, but not both. (Possibly due to some of them creating game breaking combinations, such as Speed Boost Blaziken, which through breeding also has access to Swords Dance and Baton Pass.) Within the Dream World tier in the competitive battling circle, however, both are allowed in the spirit of simulating a theoretically "complete" metagame. This most likely won't be the case with official tournaments to come in the future, as Nintendo uses different rules than the fandom.
 * The moves Double Team and Minimize would improve evasion (with enough use, could reduce all hit chances to 1/3 their original value), which basically dominated the first gen Metagame, particularly for three types - Psychic (the original Game Breaker type), Water (which only fears Electric and Grass), and Grass (due to abuse of health-draining moves). The second generation introduced an always-hit move of the new Psychic-beating Dark type, and the third gen introduced such moves to hit all three types (Ghost, Electric, Grass, and Flying).
 * Speaking of types... Psychic was ridiculously broken back in Gen. 1, for a couple of reasons. Firstly, its only weakness was Bug, and there were very few Bug-type moves available, very few actually decent Bug Pokémon, and the best ones couldn't actually learn any Bug-type attacks. Secondly, Special Attack and Special Defense were only the single Special stat, and many Psychics had high Special, allowing them to give out and absorb insane amounts of Special damage. Incidentally, this also made the move "Psychic" fairly broken, as it lowered the Special stat, causing foes to take and give less Special damage. Naturally, Gen. II did quite a bit of fixing to this: Ghost became super effective against Psychic like it was supposed to be, and the two new types, Dark and Steel, were immune and resistant, respectively, to Psychic moves, with Dark being super effective as well. More usable Bugs were introduced, along with the Fury Cutter TM, which could be learned by quite a few Bug-Types. Also, Special was split into Special Attack and Special Defense, and Psychic only lowers Special Defense.
 * Final Fantasy VI had a major issue with Gau, a character who normally can't equip weapons but has a high innate attack power to make up for it, and the Merit Award, an accessory that allows its user to equip any type of weapon or armor in the game. When Gau had the Merit Award in the original version of the game, you could equip him with a weapon. Not only did this dramatically boost his attack power, but it also led to some very bizarre Game Breaker combos, such as the legendary "Wind God Gau". Later remakes of the game prevent Gau from equipping the Merit Award, sadly enough.
 * Gogo, while not nearly as Game Breaker status as Gau, could also achieve "Wind God" status with the Merit Award. This managed to last into the Playstation re-release, but was finally blocked in the GBA update. Another, separate rule patch was that of "Psycho Cyan", but savvy players managed to find an alternate means of triggering this glitch anyway.
 * Left 4 Dead had an issue with melee shoving in VS mode. Players were literally shoving zombies for the entire game instead of actually using their guns, which made it a huge hassle for zombie players to approach and attack since they would get shoved to death. A patch then introduced melee fatigue, where survivors would have to wait before shoving again if they kept shoving too many times without stopping. This mechanic was made as a main feature in all game modes for the sequel.
 * The sequel also had a few things patched for VS mode due to complaints. Explosive ammo was removed due to survivors using the special ammo only on special infected, which basically meant that the survivors could not be touched due to the explosive ammo stumbling the zombie players. Using defibrillators would induce a 25 point penalty per use for the survivors. Spitters that spit their acid into a moving elevator would potentially wipe out the survivor team since they had nowhere to move away from the spit, so a patch was made where spitting into a moving elevator would make the acid quickly fizzle out to prevent a cheap win.
 * The sequel also made it where melee weapons were not very effective on a Tank in order to encourage more gunning and running when survivors fight a Tank. Before this patch, survivors would use melee weapons (which ranged from the practical, like a sword, to absurd, like a frying pan) to kill a Tank quickly because each hit took 10% of the Tank's health off, which the Tank could then die in 10 hits. With 4 survivors using melee weapons all at once, it would be quite easy to drop a Tank, which frustrated Tank players in VS mode. A patch addressed this issue where now melee weapons only do half the damage they used to against a Tank.
 * The Jockey gained a slight buff after complaints from players in VS mode came pouring in; The Jockey's main attack is to latch onto the survivors and ride them somewhere else while damaging them every second. The problem was the Jockey could be shoved off his victim (which is how it works) before he could do any damage at all if survivor players were quick enough. One patch later, the Jockey can now damage survivors as soon as he grabs them.
 * Something similar happened with the Smoker. The Smoker does damage by grabbing survivors with his tongue, pulling them toward him and trapping them. Originally, the Smoker couldn't cause damage to the player until his tongue attack fully retracted, implying that the tongue itself does no damage, but rather the damage comes from the Smoker hitting the survivor directly. Other survivors, however, were freeing their friends from the Smoker's tongue long before it reached the Smoker, so the attack was changed so that the survivor also takes damage during the dragging part of the attack.
 * The Witch in the sequel had received a buff for Realism VS mode after people complained that the Witch was too easy for survivors to kill. Now Witches in Realism VS cannot be instantly killed with a head shot.
 * When Survival mode was introduced in Left 4 Dead, people abused exploits and glitches in the maps by placing themselves in areas that the zombies could not "see" them at (players that are "off" the map are considered non existent by zombies), thus they could earn gold meals too easily. While some of the maps were patched to plug up the exploits, many others did not get detected. The sequel upgraded the AI Director to detect cheating in Survival mode where it will spawn Spitter acid onto a player that is not in the map or are in some spot that the zombies can't reach them and if the player avoids this check, the AI Director will just outright damage players until they get back to playing fair.
 * In Team Fortress 2, the Gloves of Running Urgently gave the Heavy a speed boost when wielded, bringing his speed up from "extremely slow" to "about average". Another item, the Buffalo Steak Sandvich, was released later that temporarily increased the Heavy's speed to above average speed. These effects, when used together, allowed the Heavy to become one of the fastest classes in the game. Now, eating a Buffalo Steak cancels out the effect of the GRU.
 * The Spy can turn invisible during which he is not able to use any of his attacks but originally he could still taunt while invisible. When the Sniper/Spy update gave him a taunt that could instant kill enemies, taunting while invisible was quickly edited out.
 * Mario Kart had the problem of snaking. It was a fan made technique where the player performs a power slide on a straight road and builds up a mini-turbo quickly, releases it, and then does it again in the opposite direction, doing this back and forth until they hit a curve. Mario Kart Double Dash had this and it was even more apparent in Mario Kart DS where the best time trial records came from snaking and everyone online always snaked with the same specific characters/karts. To address the issue, Nintendo made it where in Mario Kart Wii, mini-turbos could only be built up by maintaining the power slide in one direction until it gained enough power instead of wiggling the control stick back and forth quickly.
 * Mario Kart Wii created a new problem with the bikes. Players quickly found out that popping a wheelie gives a small boost in speed and if it was done enough anywhere, they could boost so much that they can stay ahead of players that didn't do the same or were using a kart (karts can't wheelie). In theory, bikes are supposed to lose a ton of speed if they are bumped into while popping a wheelie but this rarely happened in the hands of skilled players. Mario Kart 7 got rid of bikes entirely due to this.
 * The Fake Item Box, which is supposed to fool players by thinking it's a real item box, had been in the Mario Kart series for decades, but it was removed in Mario Kart 7. This was mainly due to the item working a bit too well where players can place the fake box inside real item boxes all the time and basically be guaranteed a player would always fall for it and since it was a big box, it could also be used on narrow paths or before jumps so players could never avoid it at all compared to a smaller item like a banana peel. The fake box became completely useless in Mario Kart DS due to players being able to spot it on the map on the bottom screen and with Mario Kart 7 using the map screen again, the fake box would be useless. With all the reasons listed above, it's understandable why Mario Kart 7 got rid of the item.
 * Prototype has a thermobaric tank that can destroy any building in one shot. There is a Kill Event that involves using one. After doing the event, the player is left with the tank and 50 rounds for the big gun. Patch: If you use the tank to destroy a military base or infected hive, the tank will inexplicably vanish, preventing you from cleaning up the entire map with it.
 * Due to the infamous amount of infinite combos and glitches that dominnated competitive play for Marvel vs. Capcom 2, Capcom's made a point of patching infinite combos out of Marvel vs. Capcom 3.

Non-Gaming Examples
"School Rule No.145 : No boy is to enter the room of any girl. School Rule No.146 : No girl is to enter the room of any boy. School Rule No.147 : (provisional) : It has been pointed out that our injunction to 'read boys for girls, and vice versa', can, if taken together with the two previous rules by someone with little to do but argue, mean that no pupil is to be in any room at all. This was not the intention. No pupil is to be anywhere except where they should be. A girl is defined as a young person of the female persuasion. School Rule No.148 : Regardless of how persuaded he feels, Jelks Minor in Form IV is a boy. School Rule No.149 : Arguing over the wording of school rules is forbidden."
 * The International Obfuscated C Code Contest added a rule in 1995 that required all submissions to have source code at least one byte in length. Why? In 1994, "the world's smallest self-replicating program" won an award for "Worst Abuse of the Rules" by being zero bytes in size. Another rule, banning machine-dependent code, was added after the first winner in 1984 wrote the entire main program as a block of PDP-11 machine code.
 * Several ad hoc laws arguably fall under this trope, especially those which are quickly struck down by the country's respective supreme court.
 * This applies to the US Constitution; for example, the Eleventh was passed to fix a loophole in Article III which allowed residents of one state to sue other states in federal court when states were normally immune from suit. The people suing? The State's creditors.
 * The 16th Amendment is another example. Federal income taxes had always been permitted under Article 1, Section 8, Clause 17, and had even been ruled to be "indirect" taxes not subject to apportionment as early as 1875. However, one really really wonky 5-4 Supreme Court decision declared taxes on income derived from property to be equivalent to a tax on the value of the property itself, and therefore a direct tax subject to apportionment. The 16th Amendment was drafted specifically to plug that loophole and re-classify all income taxes as indirect taxes regardless of the income's source.
 * There's a law in the UK which specifically bans the operation of a hand-held digital voice recorder while operating a motor-vehicle. Can't help but get the feeling this was only enacted due to someone being a wise-arse with a particularly powerful police officer.
 * In Canadian law, it's illegal to give alcohol to a moose. You have to wonder...
 * If stating what a law does sounds ridiculous (such as "you can't put an ice cream sandwich in your back pocket"), it's probably one of these. The given example came about because of horse theft, which is a crime (understandable, since it's theft). If an animal wanders onto your property, it's yours. So if you want a free horse, all you have to do is bait it in a nonobvious manner (such as allowing it to smell the food in your pocket), and walk home, allowing it to follow you.
 * Even science and math have been known at various times to have Obvious Rule Patches. A couple of the famous ones:
 * Euclid's Elements, which was the geometry textbook for 2,000 years, begins by assuming some axioms and postulates that are obvious enough to make a solid foundation—with one exception. Euclid's fifth postulate is clumsy and not at all self-evident. Countless mathematicians over the years tried to derive the "parallel postulate" from the others instead of assuming it. But the old Greek's intuition was right. The postulate can't be proven or disproven that way; if you choose a contradictory postulate, you get a "non-Euclidean" geometry that's perfectly consistent.
 * Betrand Russell essentially broke set theory with his paradox: does "the set of all sets that don't contain themselves" contain itself? To escape this paradox, mathematicians had to put restrictions on what constituted a set. The current system basically says no set can contain itself—anything big enough to do that is too big to be a set, and has to be a "class" or some such. Some mathematicians find this unsatisfying, and the debate over whether there's a better solution continues.
 * The underlying nature of Russell's paradox unfortunately indicates that any better solution will also need to be logically "patched".
 * Should the number 1 be counted as a prime number? There's a case to be made either way, and in fact it was widely considered prime until quite recently, per the classic definition ("a number whose only factors are itself and 1"). But 1 doesn't act like a prime in most of the ways we need primes to act; in particular, it has to be left out if we want the Fundamental Theorem of Arithmetic to work. Thus we now define primality in ways that are less intuitive but exclude 1, such as "a number with exactly two factors" (and hence, 0 is right out).
 * The Discworld's Assassin's Guild Diary has School Rule 16: "No boy is to keep a crocodile in his room." Followed by rules 16a to 16j to counter various forms of Loophole Abuse, from the obvious ("16a. No boy is to keep an alligator or any large amphibious reptile in his room"; "16c. Nor in the cellar.") to the outlandish ("16h. No boy is to convert to Offlerism without permission in writing from the Head Master." [Offler is the Discworld's Crocodile God])
 * According to Night Watch, the Assassins' Guild School is now co-ed, so that rule would have to have been rewritten to avoid girls keeping crocodiles in their room and pointing to Rule 16's use of the word "boy".
 * Which, when they added "Read boys for girls" as a note to the list, led to this:


 * This is surely a Historical In-Joke referring to Lord Byron. He wanted to keep a dog when he was at Cambridge, but school rules forbid it. He inspected the rules carefully and found there was nothing prohibiting pet bears, so he got one. It's unknown when Cambridge applied the highly-necessary patch.
 * In 2008 when the State of Nebraska tried to implement a Safe Haven Law it neglected to notice that its definition of "children" included anyone 18 or younger which resulted in 36 teenage children being driven in from out of state and abandoned at Nebraska hospitals. The law was patched to exclude older children later that year.
 * In 2010, the polar bear was granted the status of Threatened under the Endangered Species Act...with a rider attached by Secretary of the Interior stating that the bear's new status couldn't be used to sue oil companies or greenhouse gas emitters (arguably, the two biggest threats to the species). The environmental activist organizations that had planned to do just that were not amused.
 * In many places, there are obsolete, oddly specific, and/or downright weird laws that are still on the books, many of which are clearly patches created due to some Noodle Incident or another. One has to wonder what prompted lawmakers in San Francisco to prohibit elephants from strolling down Market Street unless they're on a leash or wiping one's car with used underwear.
 * The World Fantasy Award for Best Short Fiction is an extremely prestigious award intended for short stories, but was originally only defined as "speculative fiction under 10,000 words". That is, until 1991, when the judges selected Neil Gaiman and Charles Vess' "A Midsummer's Night Dream" issue of The Sandman, which (horror of horrors) is a comic book. The World Fantasy Convention sniffily changed the rules almost immediately, relegating any future graphic novel submissions to the Special Award: Professional category. This means the The Sandman is the only comic book that ever has or ever will win this particular award.
 * According to Gaiman, "It wasn't like closing the stable door after the horse had gotten out, it was like closing the stable door after the horse had gotten out and won the Kentucky Derby."
 * In 2011, UK supermarket chain Tesco ran a promotion that if whatever they had happened to be cheaper at its competitor Asda, they will pay you double the difference (e.g., an item that costs 8 pounds but is only 5 at Asda would earn you 6 pounds). However, the difference in prices could be big enough that shoppers would get back more money than they spent. Naturally, many savvy shoppers exploited this by finding products they didn't even need but potentially gave them the biggest profit and using that to do their actual grocery shopping. Tesco had since put the difference cap to 20 pounds.
 * In 2009 a large German electronics chain ran a promotion where you could buy any product without the Value Added Tax (currently 19%). It turned out, however, that a company can't just waive the VAT, they had to pay it nontheless. The products were just discounted by the amount of the VAT. Customers looked at their receipt and found that they indeed payed the tax, so they went back to the markets and got _another_ discount for the taxes. Needless to say they added a clause for that in their next promotion.

Literature

 * In Ender's Game, Ender's final battle as commander pits his Dragon Army against two armies combined. Ender discards all combat strategy and has his boys move as quickly as possible to perform the victory ritual. Since nobody had considered doing this without defeating the opposing army first, the other team is confused enough for him to win. He is promptly told that starting in the next battle fought at Battle School, it would not be possible for an army to perform the victory ritual without first defeating or disabling everyone in the opposing army.

Reality Television

 * On The Amazing Race, limits on how many Roadblocks a racer could perform were instigated after Season 5, after the three women who made the Final 3 that year performed a total of three Roadblocks combined.
 * In Season 1, teams were only allowed to buy one set of plane tickets, and weren't allowed to switch, even if they found a faster flight or their original flight was delayed. This was changed on the very next season, and multiple flight bookings has become an important part of the Metagame ever since.
 * The first two seasons had no rules in place for when a team's car broke down. These were instigated in Season 3 after several time credits were issued in Season 2 (including one that saved Blake & Paige from an elimination, which they recieved after Paige threatened to sue).
 * After Season 3, it became standard on selling tasks, where teams had to reach a certain amount of money made, for each individual item to have a minimum amount it could be sold for. This was after Ken & Gerard completed such a task by selling massive amounts of fruit for what would average out to be very low prices, and repeatedly going back to the stall to get more to sell.
 * Ties were disallowed after Season 4, to prevent having to give out multiple prizes for 1st place ties, and, more importantly, to keep two teams from accidentally tying for last.
 * After All-Stars, where two teams horribly exploited the ability to take locals along on the leg with you to help with navigation and other tasks, bringing locals along in your vehicle was made against the rules.
 * After Nat & Kat on Season 17 were Genre Savvy enough to take detailed notes throughout the race in anticipation of the Final Exam Finale, Season 19's Final Exam Finale instructions specifically forbade the use of notes. (There was no Final Exam Finale in Season 18.)
 * Other minor changes were made to keep teams from taking advantage of loopholes, such as buying cellphones from locals (which Rob & Brennan did in Season 1) or switching their damaged car for another team's car at the Pit Stop (Dustin & Kandice in Season 10).
 * In Survivor:
 * The hidden immunity idol mechanics were changed. First making it so that you could play it after the vote. Then, putting the limitation that you couldn't use it beyond the final six because it more or less gave Yul a free ride to the final three, since everyone was afraid to cast a vote against him for fear of the idol being played. Then, changing how the clues were hidden due to Russell's obsessive idol hunting. (Except they appeared to have forgotten it in Redemption Island and later; or later players were just that good to have found them in the first couple episodes.)
 * After "Purple" Kelly and NaOnka quit in Nicaragua, the rules were amended so that quitters can be banned from sitting on the jury if production felt it was appropriate. And typically; you can guess that unless you're trying to pull a Thanatos Gambit or are having a severe physical or mental breakdown, that'll probably be...never.
 * Reducing the eligible age to 18. (Although this hasn't really affected gameplay; you'll notice that several contestants have been below 21 in the game after Fans vs. Favorites.)
 * Not using the "purple rock" tiebreaker (where, in the event of unresolved tie, elimination is by random chance with everyone but those voted for at risk) in the final four because the one time it was used in Marquesas, Paschal was eliminated without having a single vote cast for him in the entire game.
 * Tiebreakers in general; although the spectre of the Purple Rock (as well as confirmations/sepculations by Cirie that they still do use it outside the final four) causing people to betray their alliances to avoid it. You'll notice that for some reason, people are quite afraid of forcing a tie outside of the final four that can't be solved by a simple revote (such as John changing his vote for Laura in Samoa, Russell being voted out first from his tribe in Redemption Island, and Cochran turning on his tribe in South Pacific).
 * Supposedly, someone smuggled something into the game in their luxury item (or used their luxury item in a rather creative way) to have fire.
 * In Season 2, Australia, contestants could bring a personal item. Colby brought a Texas flag that doubled as a tarp... It, along with all the other shelter items, got snatched mid-season.
 * Making tribal switches more common to shake the game up a bit.
 * The Final Two became the Final Three. While not all fans like this, Probst says that this was so people would have to face a competitor and not just drag The Load into the finals. Chances are, everyone's thoughts towards Courtney in Exile Island (intending to bring her to the finals because everyone hated her) made the producers think. Probst has pointed out there have been plenty of seasons where everyone complained the final two was a wash anyways, one of them conveniently being Exile Island. Again, this didn't stop Earl from claiming the first uanimous victory against two disliked players and Rob from pulling the two dumbest and laziest players to the finals.
 * This was also done as a result of Fan Dumb complaining about "Blowout" final twos because people had on many different seasons said that the winner was pretty obvious, nobody would've voted for [insert second place winner here], and the final tribal council was essentially just Padding because it was obvious that [insert winner here] had it. Or people just pulling What Measure Is a Non-Badass? when the fan favourite or most likely winner finished fifth-third place and a person deemed "undeserving" won.
 * In the American Big Brother:
 * After Season 3 where the jury voted 9-1 in favour of Lisa, the Jury was reduced to 7 and sequestered away from the game and unable to watch the show. The reason the jury voted in such a way was that they saw what Danielle was saying about them in the diary room and was angered.
 * The Power of Veto was made into the Golden Power of Veto permanently after Season 3.
 * Another veto example - Backdooring. In season 5, the houseguests realized that you had to pick the veto players yourself so you had full control over the players in the competition. So in order to get rid of Jase, the houseguests made up a plan and nominated two people who would have used the veto on themselves, or their other alliance members who'd have used the veto anyways. They then proceeded to pick players for the veto who would use the veto on their friends or were in on the plan and would use it anyways and evicted Jase without even letting him have a chance. The rule change was that Houseguests actually had to draw names out of a bag and only if they picked a "Houseguests Choice" Token could they choose themselves.
 * A very subtle example, but notice that the houseguests are cutting with plastic knives. This was because of a Season 2 incident where Justin held a knife to another houseguest's throat and said "Would you mind if I killed you?"
 * If someone is expelled or leaves when evicted players go to the jury, their vote at the end is given to the viewers and is used as a tiebreaker.

Sports

 * The baseball rules committee instituted the Infield Fly Rule in 1895 to block a specific Game Breaker in which an infielder would let a fly ball drop and go for the easy double play (or, should the runner choose to run, catch the fly ball and throw the runner out before he could tag up for an equally easy double play) instead of just getting the one out that would normally result. Which makes this Older Than Radio.
 * Arguably the fly ball rule itself is such a patch (albeit an even older one)--it means batters can't just hit the ball straight up and run to first base before it comes down.
 * Currently there's a minor league pitcher who can pitch with both arms. Which causes problems when he's facing a switch hitter, because switch hitters hit from different sides of the plate depending on which arm the pitcher throws with and this pitcher pitches based upon which side of the plate the hitter hits from. So minor league umpires have been forced to create a brand new rule forcing both the hitter and pitcher to declare before the at-bat, and only allowing one change of side for each player. An interesting case, since rather than this patch being the result of one game breaker, it's the combination of two slight advantage-gaining tactics that independently would work just fine, combining to break the game.
 * The England cricket team of the 1930s discovered "Bodyline" - a tactic where instead of aiming for the stumps, the bowler just pitched lots of very fast, painful balls at the batter's body, forcing him to move out of the way or deflect the ball towards nearby fielders. As a result several new rules were brought in, restricting the number of aggressive balls allowed per over and the positioning of fielders.
 * Not to mention, the 'underarm incident'. In order to deny the opposition the remotest chance of a drawn match (which would have required a six - difficult even without the pressure), the bowler rolled the ball at the batsman instead of the usual overarm bowling action. The rule disallowing underarm bowling had been omitted from the Australian verion of the rules for some reason... the rule was quickly instigated following this.
 * Dennis Lillee's heroics with an aluminium bat led to the rule: "The bat shall be made of wood".
 * Any rule introduced by the International Cricket Council invariably ends up requiring a patch. The most hilarious example is the so-called "Powerplays". Since the games were becoming boring during the early years of the 1990's, ICC introduced a rule restricting the number of fielders in the outfield in the 1st 15 overs ("powerplay"), encouraging more attacking batting. That eventually led to the game becoming monotonous in terms of strategy, not to mention making it boring during the rest of the innings. This was patched to allow 20 overs of powerplay, but the timing of the last 10 of those could be chosen by the fielding side, which led to nearly everyone invariably getting them done with at the earliest. This was patched again and now, the batting side was allowed to choose 5 of those overs. This was abused again, and led to another rule patch, which now restricts when these powerplays could be taken. Don't expect that you have heard the last on it.
 * Numerous sports - among them football, ice hockey, American football and rugby - have hastily added and often infamously complex offside rules, to prevent the various Game Breaker tactics employed that allowed the ball to be passed straight to the goal, circumventing the defence.
 * Common patch rules have been to force both teams to attempt to score rather than just stall. Football's downs system dates from the 1880s or so (look up the "block game"), pro basketball got the shot clock in 1954 after an infamously stalled game (when the Fort Wayne Pistons outlasted the Minneapolis Lakers 19-18 in a 1950 NBA game; the teams scored just four points total in the final quarter). Few such measures have been really successful in soccer. In league play, making a win worth 3 points rather than 2 (a draw being worth 1), the change being made in 1981 in the (English) Football League. In knock-out tournaments, using the "Golden Goal" in extra time, where the first goal scored ends the match, had the opposite effect; it ended up encouraging defensive play to avoid conceding a match-losing goal.
 * Soccer has the back-pass rule. FIFA introduced it in 1992 to keep players from passing the ball back to their goalkeeper and grabbing the ball to waste time. It was supposedly put in place because the 1990 World Cup was full of boring time-wasting.
 * In the 1982 World Cup West Germany and Austria went into their last match of the first round knowing a win to West Germany by one or two goals would put both teams into the next round, the other two teams in the pool having played their last match the previous day. West Germany scored after ten minutes, and the teams kicked the ball around aimlessly for the rest of the match. FIFA changed the rules so that in future, the last matches in pool play would be played simultaneously.
 * Ice hockey has an example of a rule change that corrected a problem resulting from a previous rule change. The two line-pass rule (a pass couldn't cross a team's blue line and the center line) was instituted to prevent quick passes to players hovering behind the other team's players for a clear breakaway. Teams eventually developed the "neutral zone trap" where defending players would check any player in position to receive a legal pass, forcing a player with the puck to either make an illegal pass (which would be whistled down and brought back) or carry it out himself. This slowed the game so much that in some leagues the rule was eliminated.
 * Similarly, the "Icing" rule (teams cannot shoot the puck from their side of the ice to the other end, unless it's on goal) was added after teams would just get a lead and then keep slapping the puck down the ice to make the other team fetch. It remains valid, though, when your team is shorthanded from a penalty.
 * The icing rule was again modified in the NHL in 2005. Prior to that, teams who needed to change players but couldn't (usually because they were being pressured in their own end) would intentionally ice the puck to stop play and switch lines. The new rule prevents the offending team from making any changes until after the faceoff.
 * However, there still Aint No Rule that says a team can't call timeout after an icing violation (though each team is only allowed one charged timeout per game). There is, however, a rule that states that no official (TV) timeouts shall be called after an icing violation.
 * More obviously, the NHL has the Martin Brodeur and Sean Avery rules. When goalkeeper Martin Brodeur got so good at playing the puck from behind the net, trapezoids in the four corners of the rink were created where it was arbitrarily illegal (a delay-of-game penalty) for goalies to play the puck. When Sean Avery, a professional pest, spent one powerplay parked in front of none other than Brodeur waving his hands and stick in his face to block his vision, mere hours after the game it was illegal to face a goaltender you were screening.
 * There was a similar rule patch allowing the butterfly goalie style, as a goalie by the name of Clint Benedict would drop to his knees and assume a praying position (earning himself the nickname "Praying Benny"), as there was a rule stating that goalies were not allowed to drop to their knees to block shots. However, for some unknown reason, the referees didn't penalize him simply because he claimed he was praying (religious freedom, perhaps?) and his style became so widely successful, it is now the dominant goaltending stance in professional and collegiate hockey today.
 * Go back to 1956, when a two-minute minor penalty meant two minutes of game time in the penalty box. When the Boston Bruins took two such penalties in a game against the Montreal Canadiens and Jean Béliveau scored three times during the advantage, it was a Game Breaker and the league changed the rule so that after one goal was scored, a minor penalty ends.
 * Major (five-minute) penalties, however, are still five minutes of game time in the penalty box, regardless of number of goals scored. This was kept knowing that it was a Game Breaker in order to punish major penalties, which usually involve intentionally endangering an opposing player's safety, and often involve an ejection for the offending player (in which case, one of his teammates sits in the penalty box in his stead). It's common for teams on a five-minute power play to score two or three goals, whereas it is very difficult to score while shorthanded, so a team that commits a major penalty (except for fighting, which is generally a major penalty to the same number of players on both teams, so no power play results) usually loses the game because of it.
 * There are also obvious rule patch that are not so much about preventing game-breakers as about preventing injuries or deaths that resulted when they were used. For example, American Football banning the use of the flying wedge formation in 1894.
 * There's also the offsetting penalties rules change, which has gone back and forth. It used to be that two players sent off simultaneously for the same offense (usually fighting) resulted in four-on-four play for the time of the penalties. This was abused by the Edmonton Oilers, who used famed instigator Marty McSorley to lure other players into fights, get matching penalties, and the resulting four-on-four would give plenty of room for Wayne "The Great One" Gretzky to score. To prevent this level of abuse, offsetting penalties would not result in a four-on-four situation (until years later, when the NHL wanted to boost scoring). They also added an instigator penalty, so rather than an even-numbered situation, the instigating team would be on the penalty kill instead.
 * Auto racing has a long history of these, almost from since the car was invented:
 * The Formula One rulebook includes a few basics like the driver must be in the car and driving it, the car can't be the same width of the track, and then procedes to specify almost every parameter of dimensions and engine specs to the nearest millimetre.
 * Moreover, whenever a team makes a technological discovery which gives their cars even the slightest advantage over the other teams (and which has not been yet forbidden by the rules), a patch is rushed into the rulebook to forbid it, usually enacted by the next race.
 * See the Brabham BT46B 'fan car', or the 6-wheeled Tyrrell P34.
 * During the 1960s when turbine-powered cars came onto the field and handed everyone else their asses on a silver platter. Needless to say, spurious safety complaints and absurd intake valve regulations forced them off the streets and away from the tracks.
 * Many of NASCAR's rule patches are used for safety purposes. Their two biggest examples are restrictor plates to slow the cars down at Daytona and Talladega, and mandated head and neck restraints for all drivers after the lack of such a device was a contributing factor to the death of Dale Earnhardt.
 * The Chaparral 2J forced the legendarily-free Can-Am racing series to implement a rule explicitly stating that every car can have only one engine aboard.
 * In 2012, the rules were changed to lower the height of the nose of the cars, to prevent it from striking a driver in the result of a t-bone collision. They didn't change any of the rules about the bodywork in that area apart from the nose height though, which resulted in most teams simply adding an obvious and inelegant step down to nose.
 * The NFL. Ye gods, the NFL. A committee meets every year to implement new Obvious Rule Patches to react to the previous year. Over the years, the game has accreted a whole section to patch specific actions of individual players.
 * Similarly, the IOC's Eddie "The Eagle" rule.
 * The infamous "Snowplow Game", a scoreless defensive battle between the Miami Dolphins and the New England Patriots on a frozen field in 1982. A few minutes before the end of the game, Patriots coach Ron Meyer called a timeout so that a snowplow could clear a patch on the field for the field goal kicker, resulting in a 3-0 victory. Dolphins coach Don Shula was a longtime member of the NFL rules committee, and there was a new rule in place for the next season banning the use of snowplows during games.
 * Roller derby's WFTDA rules, being less than ten years old, are constantly coming out with new rule sets featuring these. One recent example: roller derby is played in a racing-style ring, and it's a penalty to cut the track then re-enter play in front of other players. A common strategy used to be hitting opponents at the curve, forcing them to cut the corner before they could stop. A patched rule made it so you could avoid the penalty by simply falling over before skidding back into the track.
 * Basketball is an egregious example.
 * For one, early hoops lacked backboards. Backboards were created to not only make the shots a little easier, but to prevent fans on the balcony where the hoop was attached from interfering with the game by deflecting or guiding shots into the hoop. Plus, the boards were initially made from chicken wire, which caused the ball to stop dead in its tracks and fall into the hoop.
 * A jump ball was once called after every shot as opposed to the beginning of each quarter, which killed the pacing considerably and bored the fans.
 * Whenever the ball went out of bounds, it was thrown into field and the first to gain possession got a free throw. This led to both teams madly rushing after the ball—even into the crowd.
 * The shot clock was introduced to counter the four-corners offense, where the team with the lead would position four players at the corners of the offensive half-court and one at the center, then just pass the ball around ad infinitum to maintain possession and eat up the game clock. This made for a slow, low-scoring game that bored the spectators.
 * Whenever an offensive player was surrounded by defensive players on the opposing team and couldn't pass (basketball creator James Naismith stated that passing was the only legal way of advancing the ball, plus the early nature of the regulation ball made it difficult to bounce), he would simply toss the ball higher than his head, thus "passing it to himself" and avoiding getting fouled for traveling. This was seen as ridiculous-looking, however, and would soon pave the way for dribbling that would serve the same purpose.
 * Game Show Network's Extreme Dodgeball had a rule amendment only minutes after the exploit occurred. A rule to prevent delay of game would cause a team to automatically lose a player if they had both balls on their side of the court for a given (brief) length of time. David Benedetto placed both balls on edge of the opposing team's side. Thus, the players had to move forward to retrieve the balls, at which point Benedetto could easily pick up a ball without crossing the line and nail them. An all-purpose patch named the "Benedetto Amendment" was placed to prevent any players abusing delay-of-game rules to their own benefit.
 * Olympic Fencing descends from fighting with smallswords, rapiers, and sabers. Smallswords and rapiers are both pure thrusting weapons which are almost never used to slash and only really have sharpened edges to prevent foes from grabbing the weapons. Traditionally, touches are delivered by a clean thrust which depresses a button on the weapon's tip, causing a circuit to complete and a scoring light to flare. Due to the exceptional flexibility of fencing swords, sportsmen learned to "flick," or snap the weapon in a manner which caused the blade to bend around an opponent's guard and touch with the tip. The flick looks nothing like a traditional sword technique. Flicks became so dominant, especially in foil, that many fencers started calling it a "flick-fest." The sport's governing body, the FIE, patched timing rules on how long the button has to be depressed before it counts to make flicks much less viable. Most fencers consider this a good thing. Saber fencers still have a whip-over, where an electrified saber's long blade can bend and touch an opponent. Since sabers are electrified over the whole length, this means an attack which would not cut with an actual saber can still establish contact with the opponent and score a point in competition. Sabreurs are divided over whether whip-overs improve the game or not and referees have a hard time making calls on them. Was it a whip-over, an unsuccessful parry, or a remise? Good luck calling that action when it takes place in a fraction of a second. In 2000, new regulations made sabre blades much stiffer to reduce this, but it can still happen. Nowadays the FIE seems to be moving towards "if the circuit was completed, it counts."
 * Also, in saber, the cross-forward move (in which the back foot crosses in front of the front one) is banned; it is permissible in both the other weapons, and was banned in saber to prevent the fencers always fleching at each other.
 * The ban on exposing the back of the head is due to a cheat two epeeists came up with, in which they turned their back and turned their opponent, grazing their own leg on the way (which registers as a touch scored.) Nobody is quite sure why the rule patch also applies to foil and sabre.
 * The two-rock, three-rock, and Moncton guard rules in curling, which state that a rock in play but not in scoring position cannot be taken out by the opposing team before a number of rocks have been thrown in that end. The issue was that one team would get a couple points ahead and then simply take out every other rock the other team threw, leaving them no opportunity to score and making for a very boring game. As the accuracy of takeout shots and the skill of the players has improved, the number of rocks that must be thrown before the guards can be eliminated grows.
 * Plenty of such rules resulted from events described in Xavier Jackson's 5 Dumb Ways People Have Won at Sports.

Web Comics

 * In Chasing the Sunset, the rules are automatically patched.
 * This xkcd panel.
 * Penny Arcade parodies this with Scribblenauts. Tycho explains how the goal of the game is to get Starites, and you do so by writing the names of useful items (over 22,000 are available), which then appear. Gabe picks up the game and immediately writes "Starite". One appears and he wins. Note that in the actual game, doing this produces a fake Starite that's worthless.

Real Life/Law

 * In general when someone gets away with a crime via Loophole Abuse on a level under the federal one, it's quickly closed while bureaucracy stops the federal one from doing anything for all but the most major evasions.
 * The United States Constitution was vague on how succession of a dead president worked. It took almost 200 years to add the Twenty-fifth Amendment to the United States Constitution and actually codify what should happen.