The Assyrians were the first people to start using iron weapons instead of bronze which, to put into a modern perspective, is sort of like showing up for a knife fight with the Death Star. Using iron made the Assyrians so near-invincible that, really, the other guys might as well have been swinging around bananas.
A controversial element of gameplay that unexpectedly trumps all others. It is not cheating, depending on who you ask. A Game Breaker is a legit element of the game used in an unintended way, resulting in Gameplay Derailment. Contests are decided less by a player's skill and strategy, and more by whether they use the Game Breaker in question.
A Game Breaker can boost a pre-existing strategy or character and make it overwhelmingly powerful against things it would normally be balanced against -- Scissors crushing Rock, so to speak. One fan term for it is "cheesing."
For example, in a game where the player's capabilities are meant to be limited by their access to currency, an easy trick that reaps a lot of money for little effort can become a game breaker. Or a particular gun having extreme firepower, high accuracy, and a high ammo capacity; or a Fighting Game character having a fast, unblockable move with very high priority (the ally equivalent to the SNK Boss). In games with a choice of playable characters, one may be much easier than the others and allow for skipping parts of levels that other characters would have to wade through slowly.
Another example is the potentially convoluted win/make-then-sell exploit, which is common in games with customizable items. A borderline example may be the trick of saving your game before a random item appears and reloading until you get the item, also known as Save Scumming.
Patches will often seek to rectify this. However, this often leads to an outcry among players who favored the original tactic. Worse, sometimes the nerfing of one Game Breaker results in another Game Breaker being discovered as a result, prompting the developers to consider whether they should apply a patch for the second one, or undo the previous patch so the two Game Breakers will balance each other out as they used to.
Game Breakers are often controversial and subjective. Rarely do people actually agree on what is and is not game-breaking. Heated debates (or worse) over Game Breakers spread like wildfire on the Internet, or even around the house. It's obvious that the extremes of the Munchkin or the Scrub are wrong. However, there are techniques whose power is hard or even impossible to call.
Banning glitches and "unintentional" moves is often not an easy thing to do. Sometimes it can be hard to tell whether something is a glitch or not, sometimes a glitch happens so often that you'd have to go out of your way to have it not happen, and other times it can be argued that a glitch adds more depth to a game rather than less.
The upshot is that you should probably take most of the below examples of multiplayer games with a grain of salt.
Unlike video games, many Tabletop RPGs (except the most modern) have a built-in check in the form of the Game Master, who can override published rules for the sake of everyone's enjoyment; thus, with a good Game Master, no Game Breaker is possible (unless the game is SenZar). However, this naturally carries the corollary that, with a bad Game Master, the game comes pre-broken. Just what is and isn't game breaking is, again, controversial, and many GMs have to deal with a limited player base; too heavy or too light a hand may alienate players and destroy the Game Master's plan.
Compare Disc One Nuke and Sequence Breaking. A Lethal Joke Character may be one of these, as will the One Man Party if the game's balance is easily skewed. Some Boring but Practical moves/tactics may border on this, as may some Awesome Yet Practical ones too. That One Attack, when available un-nerfed to players, usually becomes this. Contrast The Computer Is a Cheating Bastard, as well as Skill Gate Characters that appear this way to newbies but can be taken apart by experts. The dramatic equivalent is Story-Breaker Power. For how Game Breaking spells/items are usually treated if in limited supply, see Too Awesome to Use. When something looks like a Game Breaker, but is actually required to complete the game, it may be Purposefully Overpowered.
A powerup that would be a game breaker, except that it only appears when the game is essentially over, is an Infinity+1 Sword or a Bragging Rights Reward—note that most examples of these tend to be single-player affairs, where there are no other opponents to become offended over it. For stats that, once boosted to a high enough degree, make the character into a Game Breaker, see One Stat to Rule Them All.
Note that this is not another word for 'overpowered'. To be a true Game Breaker, the ability in question must be so hideously unbalanced that it makes people just quit the game in disgust.
- Any game with a finite number of states and which does not make use of too much recurring randomness may be mathematically solved, resulting in a guaranteed win or draw ("perfect play") for whomever has the correct starting conditions. Once a strategy for perfect play is discovered, the game can be considered completely broken, unless played by naive players. The most well-known example of this is Tic-Tac-Toe, which any skilled player can play to a draw. Less trivial examples include Connect Four and Checkers (though in these cases, the correct strategy was found by computer and is far too complex for most humans to memorize).
- In checkers, like in Tic-Tac-Toe, it's relatively simple to force a stalemate.
- Chess and Go, arguably the quintessential games for genuises, are both theoretically solvable for a sufficiently advanced computer, as both games have a finite board and no random elements—though a computer powerful enough to perform the necessary calculations would be a orders of magnitude better than anything available with our current level of technology (the high branching factor in Go makes intractable to analyze with the methods used for Chess, since you rapidly get too many options to explore via lookahead in any reasonable timeframe, with no obvious way of pruning 'bad' choices quickly).
- Card Battle Game
- Fighting Games
- First Person Shooter
- Massively Multiplayer Online Games
- Real Time Strategy
- Rhythm Games
- Role Playing
- Shoot Em Ups
- Survival Horror
- Tabletop Games
- Third Person Shooter
- Turn Based Strategy
- Wide Open Sandbox
- Game Breaker