AI Roulette

One of the three methods an AI uses to perform moves and functions is to simply pick moves at random. For some simple foes, this is fine, as the player probably won't notice. But the more complex or varied the enemy, the more likely actions will be chosen that would never be performed by any intelligent and sane human, or any sufficiently advanced enemy AI.

Lower the player's physical defense? Let's use magic! Put them to sleep? Wake them up the next turn! Have victory one turn away? Run like a chicken! Even if an enemy possesses an attack that will effectively ensure defeat for your team if used first, it's perfectly possible that they won't bother to use it until it's too late, or even not at all.

Warning: AI Roulette occasionally can have a run of competent moves in the same way you can have long streaks of one color in true roulette, and for the same reason. AI Roulette is usually laughable, but if the AI is having a lucky streak when your party (esp. a beginning party) is fighting it, you'll stop laughing. In particular, some bosses are only vulnerable when they perform a specific move; this trope can result in controller-tossing rage when the AI Roulette doesn't come up with this move.

There are several reasons that this trope may be in use:
 * It takes less time. Complex AI routines would require a lot of coding for each individual creature to use its attacks most effectively, which increases the time it takes to create a new monster. In games with hundreds of different creatures (even if some are Palette Swap creatures), AI Roulette is a reasonable alternative to writing hundreds of AI routines.
 * The AI would be very predictable otherwise. No matter how sophisticated the AI, if the same situation always causes the same reaction the player will learn the pattern and anticipate it. A little randomness makes the game more challenging, in a way that cannot really be described as fake.
 * Execution speed. Online video games may be host to thousands of players encountering hundreds of thousands of computer-controlled entities at the same time. AI Roulette may provide a performance advantage because it keeps the server from being bogged down with conditional trees. Even simple additions to AI can result in doubling or tripling server load, and consequent game slowdowns.
 * Keeping things somewhat fair. Computers don't make mistakes, and sometimes have an unfair advantage; when monsters know your weaknesses or have devastating attacks, using the right skills all the time - using its strongest attack nonstop, breaking your best armor, going after your weakest characters, exploiting your elemental weaknesses, gaming the counterattack system - would result in incredibly frustrating difficulty.

Not related to Gambit Roulette or AI Is a Crapshoot. Compare Artificial Stupidity


 * Enemies in Final Fantasy XI generally pick attacks and spells at random. Sleepga spells can render an alliance useless, and the mob could go to town on targets one-by-one... if they could only remember to not cast any damaging Area-of-Effect spell, which wakes everyone up. Sometimes they even use Sleepga after casting Poisonga, which makes sleep ineffective due to poison damage keeping people awake. Some Notorious Monsters, however, either have only one spell, spells of a specific element, or a very small set of spells that maximize the NM's performance. At least one NM is actually scripted to cast Sleepga 2, then Thundaga 3 for massive AoE damage.
 * FFX suffered from this short cut as well. Although more commonly the bosses were a combination of AI and randomness. (IE random single damage attack followed random AoE attack followed by random buff, heal if low health) The final boss in that game has an attack that reduces your entire party to 1 HP. Potentially dangerous, but not if he uses it multiple times in a row...
 * Of course this was somewhat offset by so many of the big boss level enemies in FFXI having moves that are essentially "You lose if I use this attack". Being randomly woken up after being slept by a low damage spell means you get to live at least as long as it takes for the AI to decide to give the wheel another spin.
 * Bard enemies are funny. Lower level ones are more prone to use songs that are useful, since that's all that is available to them. Higher level ones can waste an entire 8 seconds casting a MP restoring song on themselves. Which they are incapable of using.
 * This is mostly due to a flaw in Bard monsters and enemies with MP in general: Bard enemies pretty much never have a subjob that uses MP(Not even White Mage, which is what player Bards are expected to have), and any monster that has MP has MP reserves so ginormous that MP restoration is a moot point.
 * Although some strategies for soloing certain things not intended to be soloed (such as Genbu) involve running them out of MP eventually. But compared to players, mobs have at least 10 times the MP, and bosses can have innate MP regen that makes trying to run them out physically impossible.
 * In fact, that's how most enemies in the entire series act, though some bosses would be subjected to certain rules (such as only being able to use a devastating effect every 5 turns with combat messages warning the player).
 * In the Sonic spinoff game Shadow the Hedgehog, the Egg Dealer is LITERALLY this. Its attacks are decided by hitting buttons (using a homing attack) on a slot machine that's on its front.
 * Enemies in Dragon Quest VIII, even bosses, paid little attention to the state of the fight. They'd use a special move removing all effects on the party, even when there are none. They'd cast buffs on themselves when they're about to die anyway. They'd call for backup even when their party is already full, and other pointless actions.
 * That is, in fact, emblematic of the entire DragonQuest/Warrior series.
 * In the original Dragon Quest IV, this also applied to your allies. In order to represent that everyone aside from your hero was an experienced warrior by the time you recruited them in Chapter 5, the player only got to directly control their Heroic Mime. All the other heroes had their own AI, which... didn't work out that well in practice. Such as having team Cleric Cristo/Kyril constantly casting his rarely-hitting insta-death spell against bosses. Thankfully, they added a manual command option in The Remake.
 * Even the original NES version had a Game Genie code that allowed manual command.
 * So it's one of the few cases of a Game Genie fixing a game instead of breaking it wide open?
 * In Pokémon Red and Blue, your very first battle against your rival essentially comes down to luck, as they can either attack or use a status lowering move. Whether you will win comes down to how much they will use their non-directly damaging move.
 * Well, not really, since you could take out a Potion from your computer and heal, an option which isn't mentioned at that point making it a Guide Dang It.
 * The move Metronome is this. Move that is a wrath of Pokémon equivalent to the God has the same chance of being called via it as the move that has no effect whatsoever.
 * As the game progresses, certain moves are appropriate only in the rarest of situations, such as Gravity. At other times, the 'Rock-Paper-Scissors' elemental weaknesses prove this trope. For instance, when the opponent's Fire-Ground combination Pokémon decides to square off against your Rock-type, he's just as likely to use a Fire move (which does little damage to you) rather than a Ground move (which will probably KO you quickly).
 * Interestingly, Gym Leaders are smart enough that any attack that is weak against the opponent is removed from their roulette.
 * In Generation I, this was taken a step further; pokemon used by high level trainers are programed to use whatever move has the best type advantage above all others, even before considering whether or not that move actually does damage. This was especially noticable with the Elite Four, where you'd see their pokemon use nothing but nondamaging psychic moves, such as Agility, Amnesia, and Barrier, simply because you brought out a Fighting or Poison type.
 * Trainers in the first generation with certain Pokémon, such as Spearow or Kadabra, would use Whirlwind or Teleport, despite the fact that auto-flee moves don't work in Trainer battles. Whirlwind eventually gained a Trainer battle effect that's more annoying than anything.
 * Truth is, this varies from game to game and trainer to trainer... among the AI trainers. However, wild Pokémon will always use an AI Roulette. This is probably justified by the wild Pokémon not having the decision-making skills of humans.
 * And it falls apart again when you realize that some Psychic-types are supposed to be as smart or smarter than people, but still use the Roulette when wild.
 * Graveler on the Victory Road in GSC have been known to blow themselves up rather than have to deal with a Bug/Poison type like Spinarak they have a 30-level advantage over.
 * The Roulette that AI trainers use prevents them from using moves that will be not very effective... which can make them even dumber than if they just used random moves. In Yellow Version, Giovanni has a Nidoking and Nidoqueen that, when faced with a Grass/Poison type like Bulbasaur, will only use Leer or Tail Whip due to what their other moves are. When you don't understand the Roulette, seeing them beat your Pikachu in one hit and then be taken down by a level 10 Bulbasaur is utterly baffling.
 * The battle system in Earthbound relies on this to make fighting some enemies easier. Many enemies (with few exceptions) have "do nothing" type actions in the list, such as furrowing one's brow or falling down. These are chosen from an enemy's list of attacks just as often as their regular attacks are, so it's possible to get lucky and have an enemy spend several turns idling.
 * Given the atmosphere of the game, this practically falls under the "Rule of Cute", if there were such a thing.
 * Then there's the Clumsy Robot boss, which has one devastating attack and so many "do nothing" moves it could be considered a Lampshade.
 * Of course, this also means that if you get unlucky and Clumsy Robot uses the missile, say, four times in a row, even the rolling HP meters won't save you.
 * There are also some enemies that use a set pattern to attack, such as the Robo-Pump and Final Starman.
 * In the Microprose Magic: The Gathering game, the AI has a particular talent for snatching defeat from the jaws of victory because it randomly selects its moves. It's particularly amusing to see it countering its own spells. It is rather obvious to anyone who plays that the AI does not understand the game.
 * Worse, the game also includes cards with random effects that do not exist in the regular card game. These cards are so badly designed (being fundamentally unreliable) that no sane person would put them in his deck. But of course the AI does, most notably the final boss. The only reason the boss stands a chance is because he has twenty times as much HP as you do.
 * The game-exclusive cards are, like a lot of older Magic sets, a mixed bag. But Necropolis of Azar, Aswan Jaguar, and Rainbow Knights are actually decent.
 * A common issue with City of Heroes and City of Villains mooks and bosses, especially later in the game. Rikti suffer horribly, as Mentalists will spam sleep powers on Heroes stuck in poison gas, Guardians will heal allies at full health and shield almost dead ones, and Drones can spend a lot of time running from characters with accurate ranged attacks. The Praetorians and the Freedom Phalanx tend to suffer from this, too, especially Numina and her evil counterpart. They'll beat you to within an inch of your life, turn on an invulnerable force field, and then run away.
 * The force field used by Numina and her evil counterpart is used when at low life for a certain duration whenever the cooldown is up. It's predictable.
 * This is added in deliberately for an allied NPC during the battle with Ajax. The NPC, has both a random combination of powersets (meaning that it's quite possible for it to have no offensive moves, or nothing but them), and a deliberately downgraded AI. Whether or not the will actually be a help is a Luck-Based Mission. Even if you do end up getting an ally with a functional power combination, there is a very real chance they'll spend the entire fight doing the chicken dance.
 * In Crisis Core: Final Fantasy VII, you will run into enemies on the harder missions who outnumber you 5 to 1 and have the AI roulette. Example: One of the Wutai missions pits you against 5 Silver Wutai Soldiers, who have a move called "Death Missile" that kills you in one hit unless you have that rare item that makes you immune to Death. They seem to like this move a lot.
 * Final Fantasy VI presents a unique scenario for this trope: the Coliseum, wherein the player chooses a single champion from the active party to fight solo against the enemy. The AI Roulette will then take over this character. The problem is, the more abilities (or spells) the character has, the more likely it is to perform something useless (like trying to cast Imp at Siegfried for ten turns in a row, or using Remedy or Float on oneself) or downright harmful (such as Meltdown, summoning Crusader, or Self-Destruct.) Many a player has gone into the Coliseum with a fully-leveled up Sabin, armed with a Genji Glove and a Master's Scroll/Offering, expecting to kill the enemy in one shot, only to see him cast Soul Spiral and kill himself on his first turn.
 * The most painful situation possible, however, is if the AI controlled Terra chooses to Trance herself. For some bizarre reason, whenever that happens the AI will simply sit there, letting Terra soak up whatever the enemy chooses to throw at her, for up to a minute at times. This is a triple-whammy: It wastes the precious MP Terra uses to stay in Trance mode, it essentially ruins the battle for you, and it's boring as hell to watch if the enemy can't kill her quickly.
 * In Final Fantasy VIII, after some plot events, Rinoa gains a new Limit Break ability Angel Wing which sends her into a unique berserk state: the player loses control of her actions but she gets boosted speed and magic power, (limited) status immunity, and continuously casts magic at no cost. Sounds great at first, but since berserk Rinoa selects spells entirely at random based on what she has available, she's as likely as not to cast Scan and Silence/Sleep/Confuse over high-level damage-inflicting magic. With a full stock of spells, AI Roulette therefore makes Angel Wing all but useless - but when all she has is Ultima (or Meteor!) well...
 * The Last Remnant for the Xbox 360 is an unusual case in that you, the player, are subject to partial AI Roulette just as much as the enemies due to the battle system. Though you still have command over your units, the available list of commands you can pick from turn to turn (as well as depending on the enemy you target) is determined entirely by the AI. Sometimes the commands available are entirely logical and normal, sometimes they're nothing near what you need (i.e. no healing commands when you could certainly use some), and sometimes they give you access to your uber attacks for trash enemies.
 * In Adventurers!, Eternion has an attack that allows him to nearly kill the entire party in one hit. After he declares his intent to use it again to finish them, he instead uses something else. When he expresses his confusion, Karn explains this trope to him.
 * World of Warcraft: Bosses (and mobs) that mind-control your character will then use your powers against your teammates. Druids can be forced to cast Teleport:Moonglade in a dungeon that was on another continent. Hilarity ensued.
 * There is one major exception: If you get mind controlled, expect the AI to use your longest cooldown skills just to deny your their use at a moment where they would be helpful.
 * The AI also seems unable to cast targetable AoE attacks properly and is always casting them on itself.
 * The most amusing case is with a mind-controlled Mage. Part of the time will be spent AoEing around themselves, and the rest will be spent swapping back and forth between the 3 self-only buff spells that a mage can chose between.
 * For that matter, mobs generally use their abilities at random as well. Bosses tend to be less random but some of their abilities are still used more or less randomly with a cooldown limitation preventing them from spamming the party to death.
 * Other particularly hilarious times are when the boss will force you to use a move that will break the mind control.
 * Most mind-controlled caster classes will spend a large amount of time feebly whacking their teammates with their staff or mace.
 * An accepted break in the already Nintendo Hard Shin Megami Tensei Nocturne, where some bosses could outright kill you in one round if they used the strongest attack twice. The Bonus Boss is a Luck-Based Mission.
 * This is an understatement. If it wasn't for the roulette, Back Attacks would invariably kill you every time. And enemies that could use multiple elements would decimate your party over and over again, becoming Demonic Boss in Mook Clothing.
 * This is also the case in the Persona subseries, and is the only reason Persona 3 Bonus Boss The Reaper can be killed without resorting to Armageddon. The key to surviving this fight is that it likes to waste turns using element Break spells and then refuse to exploit the new weakness. The hardest part of the fight is actually the end - once the Reaper is almost dead, the roulette shuts off and its AI goes to "Nuke'Em" mode.
 * Speaking of Persona 3 (As well as 4 and 3P if you leave Tactics on), this can be applied to your Party Members. Granted, you can tell them to favor certain tactics, and they will listen to what Fuuka has to say once she finishes her Enemy Scan, but that won't stop Mitsuru from using Marin Karin at the worst possible time. In their defense, once something not mentioned by the scan doesn't work, they won't repeat it for the rest of the fight; the downside is that their AI can't remember it won't work.
 * Intentionally done example: in Kingdom of Loathing the Quiet Healer opponent will occasionally heal the player instead of hitting him, "by force of habit".
 * The AI in Company of Heroes does this to a degree. While the AI will still use reasonably effective tactics (how effective depends on difficulty, of course), the basic plan seems to be based largely on AI Roulette. IT should be noted, however, that the AI will, on higher difficulties, still be able to completely fuck you up no matter what he does.
 * This is because The Computer Is a Cheating Bastard. At all difficulties. The most important thing the difficulty choice affects is how much the opponent cheats.
 * Beholders in Baldur's Gate 2 tend to spam their attacks mostly at random. This can be convenient when they paralyze you then hit you with their Anti-Magic eye to dispel it, but just pray an Elder Orb doesn't decide to cast Imprisonment on your main character, because We Cannot Go on Without You, even for long enough to counter it.
 * Mages also have an AI flaw that can make them seem a bit like this, although they actually adhere to a pretty strict pattern. Summoned demons register as hostile and will attack you unless you cast Protection from Evil on yourself. So they summon a demon, cast the protection, then spend all their energy attacking it because it still looks like an enemy.
 * Monsters in Monster Hunter do this on occasion (e.g. using close-range attacks when the player is far away), although it's not as jarring since most of them are supposed to possess only animal-level intelligence, and they usually do choose an appropriate action. However, their tactics are not completely random, and may sometimes come as a nasty surprise (roar to stun and immobilize the player, launch a normally easy-to-dodge beam which knocks off 2/3 of his health and sends him flying, follow up by charging him and stepping on him).
 * Spellcasters in Neverwinter Nights can be just embarrassing. Casters with access to powerful damaging spells will instead start casting 0th level protective spells like Virtue or Resistance, and target you with Daze, a spell with a 5% chance of very briefly incapacitating you. Then randomly they'll take off half your health in one hit, before going back to casting Dispel Magic on someone without any spell effects on them.
 * Golden Sun has this with all of its bosses.
 * Not quite. Dullahan, the Bonus Boss of The Lost Age, has a set attack pattern of 24 moves that he cycles through, starting the battle at one of three specific points in the cycle. Presumably this is to stop him from using Charon three times in the same turn, or worse, Djinn Storm followed by two Charons.
 * And again in Dark Dawn. He has a fixed pattern, but starts at a random point in it. He does skip two attacks in the command if certain criteria are not met, which allows for some permutation of his command queue. If you can manipulate the turn queue properly, or start at the right place already, you can use Doldrum or Ivy to lock out Djinn Storm. The rest of his attacks, however? Good luck.
 * Most of the other bosses, though, have a chance (however small) to show you precisely why summon rushing without precautions is risky by occasionally curbstomping the party in two turns. The rest of the time they put up little to no resistance to the tactic.
 * Downright painful for mooks, since they're already severely underpowered. There's a point where you just feel sorry for enemies using their non-damaging defense lowering move on your weakest character for two turns (which is actually a good idea), then attacking your strongest character the third turn, right before dying and having done practically no damage at all.
 * Lashiec from Phantasy Star IV will have you praying he attempts to cast Possession, which may or may not put one character to sleep, instead of casting Anothergate, which deals a LOT of damage to everyone. Same goes for Dark Force, with Evil Eye and Lightningshower.
 * As well as the biggest Big Bad, which may use Cancellation on you, removing the effects of your protective techniques. Resetting your party's magic defenses (if you even care about them) is far less costly than recovering from a group-damage attack.
 * Also from IV, Juza, who also acts as a Beef Gate boss. If you're not leveled high enough for at least one party member to have Gires (which is referenced specifically in a cutscene soon after the fight), he will spam Forceflash, a high-damage ability guaranteed to turn your party into chunky salsa in a few rounds. If someone does have it, the AI Roulette takes over, and he will use other attacks between Forceflashes.
 * The Dungeons and Dragons 3.5 edition book Tome of Battle include the Crusader class, which gains access to randomly selected known abilities each turn.
 * Iji's General Tor is a partial aversion. It starts off as straight AI Roulette, but the probabilities adjust to favour attacks that have already hit you as the fight goes on. Fortunately, this doesn't apply to his charged shots that you can reflect For Massive Damage.
 * A few fortunate spins of the AI Roulette is your best chance of defeating Werdna in Wizardry. Amongst his devastating attack and spells is...Zilwan, a "kill undead" spell. Since you don't have any zombies in your party, you'd better hope he decides to Zilwan you three or four times in a row, because you're not surviving much else.
 * In SpongeBob SquarePants: Battle for Bikini Bottom, there are robot boss versions of some of the characters which follow this trope. Robot Sandy can do her clothesline move 15 times before she shows her weak spot move!
 * There are several situations in Dragon Age where most characters, and even parties, can be wiped out if the enemy mages randomly cast the right spells unless the character is specifically built and equipped to have massive generic spell resistance. This isn't a completely bad thing because there are several fights in the game that would be impossible to win if the AI was intelligent.
 * * The entire SaGa series has this in droves, especially SaGa Frontier. While a few have a powerful move that they activate only after certain circumstances, they typically spam their moves indiscriminately. Battles devolve into games of chance in the hopes that they don't choose their most powerful attacks. It doesn't help that many of the bosses get multiple turns. Even some of the most innocuous low-level enemies have sort of party decimating attack they may or may not do that can result in an impromptu Game Over. MagneticStorm, any one?
 * Sports games in general are notorious for their AI Roulette, although it is much more visible in games that let you choose the difficulty (the higher the difficulty, the lower the chances of dumb AI behaviour) and team-based games (where an error by a single player or an especially smart move by one out of X guys can mark the difference between humiliating defeat and amazing victory).
 * Pro Evolution Soccer is one of the most known Sports franchises to feature this: while on the easiest difficulty sets the AI controlled players are brain dead zombies letting you do all the play and occasionally defending, on the hardest difficulty settings it's nearly impossible to predict if the opponents will leave a huge opening (even bigger than the ones on easy difficulty), perform amazing saves and shots or simply cheat with extra speed and stamina.
 * The Tag Duel gameplay style in recent Yu-Gi-Oh!! games tends towards this. To explain, a Tag Duel is you and (usually) a computer ally against two computers with 8000 Life Points and one playing field per team. You each have your own decks and hands and can use your team member's cards to your advantage when it's your turn.
 * An example: after the player has used Nightmare Wheel on an opponent's face-up Oracle of the Sun, his computer ally proceeds to use Lightning Vortex, ruining the nice set-up the player had just put into place.
 * The bonus boss of Etrian Odyssey subverts this. It has three elemental attacks, any one of which will wipe out your entire party if not blocked by the specific, one-turn-only anti-elemental technique. The only way to beat him is to memorize the entire set 50-turn-long sequence of attacks he uses so you can counter them at the appropriate time; so strictly speaking (barring an insanely defensive tactic), he's only beatable because he subverts this trope.
 * Similarly, the bonus bosses of the second and third game follow a similar pattern, only the second game's bonus boss plays this straight if you attack him at night. The third game's bonus boss also plays it straight after losing only 1/4th of its hitpoints. Since all of its moves are lethal, both common tactics for beating it involve simply shredding it in a single turn using one of the game's two most broken moves.
 * Liero's AI is entirely random. Even in tweak programs the only things that can be changed about the AI are its actions' probabilities. Needless to say, it was pretty dumb.
 * Worse yet it can force you to have to quit. This is the reason I only ever allow explosive weaponry from the start with more than one or two CPU players, because they will get locked in place trying to shoot through walls directly with plain ol' shell weaponry. At least if you give them explosives they will sometimes kill themselves with the explosions.
 * Enemies in Bookworm Adventures invariably use this tactic. And it's a good thing, too, because if they used their abilities intelligently many of them would be able to stunlock Lex.
 * An interesting very early racing game example in the days when the player was the only one capable of making mistakes exists in Sega arcade game GP Rider. While you're tasked with completing a race, much less winning it, the single-player version has you racing against a rider named "Wayne" instead of the second player. On each race, Wayne behaves differently: sometimes having good races, sometimes having bad races. This was in 1990. The ports were created in 1992. Wayne isn't a dynamic AI of the type that are in most racing games, especially simulations, due to the fact that he essentially picked "good" or "bad" riding habits uniformly in each race.
 * A speedrunner named Cosmo, while attempting a world record speedrun of The Legend of Zelda: Ocarina of Time, ran into this with the Fire Temple boss, Volvagia, during one of his most promising runs. Due to the specific sequence break he was using, he had a limited amount of time to defeat Volvagia before the game auto-killed him, which would waste too much time to catch up to the world record, meaning he would have to start over an HOUR's worth of gameplay over. So of course, Volvagia, only being vulnerable when the AI Roulette lands on certain moves, proceeded to perform anything but those moves until Cosmo's run was ruined. This happened repeatedly.
 * While a standard problem in turn-based strategy games, Steel Panthers used to really take the cake, as going harder WIDENS the roulette. It's not unheard of for a king tiger to suddenly turn around to fire at the crew of a destroyed tank while the entire enemy army is lining up on it, or to overrun a position just once, then drive harmlessly away if it doesn't succeed. In short, mid-tier difficulties were the hardest, as easy is colossally stupid, and expert-level difficulties afflicts the enemy With Great Power Comes Great Insanity as they will pound you into gravel, then randomly give you a game-winning opening, provided they haven't blown up all your guns or chased off your tank hunters. Also the AI's support vehicles have a tendency to get 'stuck' and drive in circles until they finally decide to flee giving you a LOT more time to get to them and shoot them. Sometimes you will even see such insanity as an enemy transport getting its passengers killed because it spotted 'soft targets' before the 'hard targets' and it will attempt to charge up and engage your recons with SMG fire despite the fact there is a tank or AA gun one hex over, all while forgetting to let the soldiers onboard disembark. The remake World at War fixes a lot of that, but not all.