If a {{Good Bad Bug|s}} is particularly liked by fans of a game, it might be upgraded to the status of a legitimate feature in a sequel, update, or expansion. This is a refreshing attitude from game developers, who otherwise tend to take a zero-tolerance approach to the squashing of bugs-- the exact opposite of the attitude usually taken by fans.

Of course, bugs that [[GameBreaker break the game balance]] usually aren't eligible for this, unless the game is rebalanced to accommodate them. {{Game Breaking Bug}}s are ''never'' eligible, of course, owing to making the game {{unwinnable}}. No-one likes those bugs.

'''See also:'''
* GoodBadBugs, where glitches can be used for gaining an advantage of the game or just pure entertainment.
* AscendedMeme, where those related to the source material of the meme recognize it.
* AscendedFanon, where fan-suggested ideas and stories are written into the {{Canon}}.
* ThrowItIn, which is like this trope, but happens when the work is in development stages.
* ViolationOfCommonSense, which most of these bugs tend to rely upon.

----
!!Examples:

[[foldercontrol]]

[[folder: Action Adventure ]]

* ''VideoGame/JurassicParkTheGame'' replicates the blooper from the original movie where the security camera feed on the computers is just a video file playing in a media player if you look closely enough to see the playback position bar at the bottom. The game has these on live security camera footage too.
* The 3DS version of ''VideoGame/TheLegendOfZeldaOcarinaOfTime'' contains many of the bugs from the original N64 release, such as the ability to enter certain areas that should be locked off to you. The original plan was to fix all these bugs, but many of the developers argued that the bugs were a part of how the game played and as such should be left in. In the end, any glitch that wasn't actively harmful was left in as a deliberate feature.

[[/folder]]

[[folder: Action Game ]]

* The combat system in ''VideoGame/DevilMayCry'' was born from a glitch that was removed during the development of ''VideoGame/{{Onimusha}}''. It was a glitch where you could launch people into the air and juggle them. It got cut for being out of character for the game, but the glitch was [[RuleOfCool so cool]] that Creator/{{Capcom}} decided to get some ideas from it.
** In the original release of ''Devil May Cry 3'', the player can unlock a "Super Dante" costume, which allows them to be in [[SuperMode Devil Trigger form]] as long as they want. However, while other techniques that rely on the Devil Trigger gauge (DT Explosions, Quicksilver and Doppelganger styles) were still supposed to use up its power with this costume, a glitch gave them infinite use as well. For the ''Special Edition'', while the glitches around Super Dante were fixed, a Super version of the "Legendary Dark Knight" costume was also added which kept the glitch's behavior, as an unlockable for beating the game on the hardest difficulty level.
* In the NES game ''VideoGame/NinjaGaiden'', clever players could quickly unstick and restick to a wall to climb it, even if it had no ladder. The sequels added the wall climbing skill as a default ability and adapted the game levels around it.

[[/folder]]

[[folder: Adventure Game ]]

* During a phase in which thatgamecompany had trouble getting the ending levels of ''VideoGame/{{Journey}}'' to properly resonate with playtesters, one test ended prematurely when a glitch caused the game to seem like it was over [[spoiler: right after you die in the snowstorm]]. The playtester found this false ending so profoundly moving it brought him to tears; this inspired tgc to put in significant extra effort to turn the actual ending into something equally moving.

[[/folder]]

[[folder: Fighting Game ]]

* ''VideoGame/StreetFighterII'':
** {{Combos}}, which would become a cornerstone mechanic of not just the ''Franchise/StreetFighter'' series, but the entire fighting game '''genre'''.
** Cancelling: Inputting a second command quickly before the character has finished performing the first one can lead to the second move occurring instantly, bypassing the recovery animation of the first. This technique is now the cornerstone of many fighting games, where it is possible to cancel attacks, throws, jumps and dashes into one another, to say nothing of regular combos.
** Many combo-oriented games feature a variation of "Super Cancel" which can cancel any move into any other at the cost of the special gauge.
** In a graphical glitch (initially thought so; later revealed to be a deliberately coded Easter egg according to WordOfGod) in the early installments, Ryu and Ken would occasionally throw a red-colored Hadoken instead of the normal blue. Despite no evidence that the red Hadoken did anything special (and specific WordOfGod statements to the same effect), players [[UrbanLegendOfZelda insisted]] that the red Hadoken did extra damage (or was faster or gave an extra split second of impact recoil). Capcom eventually responded by giving Ryu a flaming Hadoken in ''Super Street Fighter II'' (it sacrifices execution speed for more damage and the ability to knock down at point blank).
*** Cross-ups: In games where blocking is achieved by holding "back", a cross-up is a situation where it is difficult to judge the correct direction to block your opponent's attack, such as when attacking while jumping right over the character. Needless to say that initially this was just a design oversight, but later it was polished and promoted to another aspect of mindgaming your opponent.
* Ryu's additional moves and supers in the ''[[CapcomVsWhatever Vs.]]'' games (changing movesets to those of Ken or Akuma[=/=]Evil Ryu, invisible/explosive/multi-hadoken) are inspired by glitches or modifications created for a pirated edition of the original ''VideoGame/StreetFighterII''[='s=] ROM board, dubbed the "Rainbow Edition." There, characters could transform into other characters by hitting the start button, and fireballs had variable speed and could have their flight paths be manually controlled or rendered invisible by player input.
** Most of new Ryu's and his friends' moves in ''Turbo: Hyper Fighting'' revision of SF2 was also inspired by those hacks. It also featured a faster game speed.
* The "invisible Dhalsim" glitch (where occasionally, after doing a Yoga Fire move, the character's sprite would become invisible, unable to take or receive damage) was later incorporated into Dhalsim's Yoga Teleport.
* Roll canceling[[note]]Inputting a roll quickly followed by a special move gives the special move invincibility for whatever the duration of roll would have been.[[/note]] in ''[[VideoGame/CapcomVsSNK2MarkOfTheMillennium Capcom vs. SNK 2]]'' has become an accepted, if not vital part of high-level play. Capcom acknowledged the behavior was a glitch while the game was still in arcades but did not code it out of the Dreamcast or [=PlayStation=] 2 releases. However the "EO" builds developed for the [=GameCube=] and Xbox do not have roll cancels.
* Cody's "Final Destruction" super move from ''Alpha 3''. The move itself looks rather weird (if it connects, he will jab his opponent twice, turn around, turn back around, jab them twice again, and do it about four times before ending with a powerful string of attacks). However, it's actually a ShoutOut to a glitch from ''VideoGame/FinalFight'' where he could do this to destroy his opponents with ease. If used in X-ISM, this move changes all his attacks into his ''Final Fight'' attack strings instead.
* A couple of bugs in ''VideoGame/TheKingOfFighters'' made their way into canon. One of them is Leona's respect for Chang (she salutes him starting with ''KOF '98''; it cued some nice WildMassGuessing back in the day). Another one is Kim's midair super in ''KOF '94''; it was definitely a bug that affected other characters with midair command moves in ''KOF '94'' and ''KOF '95'', but Kim's ability to do the Ho-o-kyaku in midair has been an intentional ability in many later games.
* ''Franchise/MortalKombat'':
** Baraka's "whirling dervish" move was originally the result of a glitch, but developers liked it so much that it was eventually added to his repertoire.
** There was a glitch where Johnny Cage's uppercut fatality would decapitate the opponent twice. Developers took this a step further in ''II'', giving him his hidden ''triple decapitation'' fatality.
** Noob Saibot was DummiedOut of the arcade version of ''VideoGame/MortalKombat4'', but made unlockable (although he lacked fatalities) in the console versions, and had a couple of rather glitchy alternate costumes.
** Speaking of palette swaps, there's [[http://www.strategyinformer.com/news/11631/first-2-mortal-kombat-dlc-characters-revealed Scarlet.]]
** The legendary "Ermac" glitch, however, [[UrbanLegendOfZelda never happened]], though it became AscendedFanon in later games.

[[/folder]]

[[folder: First Person Shooter ]]

* ''VideoGame/{{Quake}}'' had the Strafe-jumping, which was a bug at the time, but became so popular that it was later the trademark of its multiplayer component. An uproar went through the community as the mechanic was removed in one patch of ''VideoGame/QuakeIIIArena'', so a new patch featured it as... well... a [[DepartmentOfRedundancyDepartment feature]], which was part of its success, along with a lot of other stuff. ''Quake Live'' even has a tutorial with many courses which rely on this.
** Taken to a ridiculous extreme in ''VideoGame/{{Warsow}}'', wherein the game engine was built from the ground up to accommodate movement tricks that started as glitches in ''Quake''.
** There's also the "RocketJump". Point the rocket launcher straight down, jump, and fire immediately after the start. The player will take an assload of damage, but wll also be flung much farther than otherwise possible by jumping. When exactly this ascended is unclear, as the third episode of Doom had a secret exit that was designed to only be accessible by launching yourself sideways off a wall with a rocket (other ways have since been found), and in VideoGame/QuakeII, there's a secret spot which can only be reached by rocket jumping. In the latter, when you land, the text, "You crazy rocket jumpers!", appears.
*** One of the single player maps in ''Quake'' had a secret area accessed by a teleporter hanging from the wall. In order to reach the teleporter, you had to fire a grenade into a small hole in the ground beneath it, and jump over it just as it explodes. So [[IdSoftware id]] ''did'' have some knowledge of this technique in mind when designing the game.
*** The ExpansionPack ''VideoGame/QuakeII: The Reckoning'' mocked it in one of their levels. In it, you would see an Invulnerability which vanished after a certain distance. A message would show up later saying "No prize for you, rocketman." The expansion is also infamous for having increased the Rocket Jump damage and distance very much.
*** ''VideoGame/{{Marathon}}'' actually had grenade jumping similar to "modern" rocket jumping, about the same time as ''Doom''. It became an ascended glitch, too, with secret areas requiring it. In lower-gravity stages, you could even use the flamethrower as a makeshift jetpack. Although you could use the ''recoil'' from the rocket launcher to propel yourself, trying to use a point-blank blast to launch you upward would instead kill you instantly. The recoil physics were nerfed in the second game's engine, precluding the "jetpack flamethrower".
*** ''VideoGame/TeamFortress2'''s Soldier was designed with rocket jumping in mind, and can acquire boots that, in exchange for losing a shotgun, improve his rocket jumping ability. The "Gunboats" reduce damage taken from rocket jumps, and the "Mantreads" turn rocket jumps [[GoombaStomp into an attack]]. Now there are also weapons for both Soldier ''and'' Demoman solely designed for rocket jumping: They do no damage to anyone, but still allow rocket/sticky jumping.
* In the update that added "King of the Hill" to ''VideoGame/TeamFortress2'', when the round went into Overtime, the announcer would [[http://www.youtube.com/watch?v=QkbN0Y1yktU repeat her proclamation of "Overtime!" over and over]] every time the point's status changed ''at all'', including whenever a player stepped on or off of it. This one was so popular that [[http://store.steampowered.com/news/2738/ when Valve fixed it in the next update a day later, they added a server option that allowed admins to keep the buggy speech if they so desire]].
** Further, an October 13th, 2011 patch added a server option to re-enable a popular bug, "Taunt Switching" (where the model for one weapon replaces another in a taunt, so that, for example, a Spy could pretend to fence with a revolver, or a Demoman could take a drink from his grenade launcher).
** The Sniper Vs. Spy update canonized the disguise kit+crouch+look up "Spy Crab" pose (in which the spy's model stretches beyond his animation skeleton) by having approximately 1 out of 10 taunts with the disguise kit use an alternate animation with the spy dropping into a crouch and making claw motions with his hands.
** The Spy class itself was inspired by a bug in the original ''Team Fortress'', where players would sometimes see other players with the wrong team's color.
** Before the Uber Update, there was an exploit for Demoman to allow him to turn sharply with the Chargin' Targe; this exploit was later turned into an item called "Ali Baba's Wee Booties". The only downside is that you don't have a Grenade Launcher.
** The Demoman's melee taunt, originally, could have him drink from anything ''but'' a bottle of scrumpy; i-ghost, a contributor to ''Team Fortress 2'', removed most of these taunts as part of a cleanup project, except when drinking from the Frying Pan, as it was deemed 'too funny' to remove.
* Early in ''VideoGame/{{Half-Life 2}}'' ''Episode One'', Alyx asks her robotic companion dog "You ''did'' do the math, right?", right before being flung across a bottomless pit into the citadel. DOG originally wasn't supposed to do anything, but a script error caused DOG to insert his head-shaking animation, ''right after that line'', and the playtesters loved it so much it was worked into the actual script.
** ''Episode Two'' has a bug with a dumpster in which a fast headcrab zombie is hiding. If the player tosses a grenade in a dumpster, the grenade will [[GrenadeHotPotato be tossed back out]]. This was discovered in playtesting, and they liked it so much that it was kept in.
** The Combine gunships had an AI glitch during testing which caused them to shoot at rockets fired from the laser-guided rocket launchers[[note]]Gunships are set to focus their fire on the biggest threat; under usual circumstances, this is the player, but as soon as s/he launches a rocket, that changes[[/note]], forcing playtesters to guide missiles [[{{Roboteching}} in all manner of odd paths]] in order to confuse the AI and hit the vehicle. This proved to be so popular that it was left in as a feature.
** In a similar act of serendipity that ended up making the game more interesting, during the airboat vs. helicopter battle, the "mine spam" dropped on the player was originally due to one of the programmers accidentally making the helicopter drop mines instead of shooting bullets. This was toned down and added to the game as the helicopter's DesperationAttack near the end of the battle.
* One sequence in ''VideoGame/Left4Dead2'' involves making your way through an abandoned sugar mill. An odd glitch caused a larger-than-usual number of Witches to spawn in the building; the testers thought this was a stroke of genius, so Valve left the glitch in and wrote the Witch's fondness for the smell of sugar into the backstory.
* A bug with jumping inertia in ''[[{{VideoGame/Tribes}} Starsiege: Tribes]]'' let skilled players reliably "ski" downhill at high speed to build up speed. When it was fixed, not only after player feedback was it quickly put back in, skiing became a trademark feature of the sequels, even being required at various points in ''[[{{VideoGame/TribesVengeance}} Tribes: Vengeance]]'s'' campaign.
** Lampshaded by [[http://web.archive.org/web/20120403165447/http://www.hirezstudios.com/hirezwp/?p=1900 this]] AprilFoolsDay post, which claims to have "fixed" the bug for ''Ascend'' even though by this point it was an absolutely critical gameplay mechanic.
** Deserving of special note is the fact Skiing went from a glitch to the core game mechanic the entire franchise is built around. ''Ascend'' has wide-open, hilly arenas that would be unplayable on almost any other engine.
* ''VideoGame/HaloCombatEvolved'' had a bug in which, when the player looked all the way down, the character model's head would instead look straight forward. This got used heavily in machinima (most notably ''Machinima/RedVsBlue''), since, particularly when used with pistols, it looked as though the character was at ease rather than constantly pointing his gun at other people. For ''VideoGame/{{Halo 2}}'' and ''[[VideoGame/{{Halo 3}} 3]]'', Bungie fixed the glitch, but added a feature that allowed a character to put his gun at a "rest" position, while the original glitch returned for the ''Anniversary'' remake of the original.
** In ''Halo 3'''s map editor Forge, people used glitches and tricks in order to place objects in order to make cool new maps. In ''VideoGame/HaloReach'' Bungie changed these tricks into features of the new map editor.
** Possibly inspired by the Honor Guard Councillor glitch in ''Halo 2'', one of the two types of hidden "BOB" Elites in ''Halo: Reach'' is white with a random armor type.
** "Grenade jumping" is the only way to reach at least a couple of the unlockables in some of the later games, as well as the only way to get the "How Pedestrian" achievement in ''Halo: Anniversary''.
* Among other things, ''{{Painkiller}}'' pays homage to the traditional quirks in FPS physics and some secrets are hidden in ways that require you to take advantage of these. You need to be able to exploit the way the hitbox reacts to almost invisible protrusions in walls to climb them with constant jumping (Asylum). You must at times resort to bunnyhopping (even in circles!) in order to gain enough momentum to leap somewhere else (Castle, Colosseum). You must remember that doing an U-turn in midair is a perfectly plausible thing to do (City on Water). Even rocket jumping has ''its own hotkey.''
* Any number of weird bugs have been adopted by the ''VideoGame/{{Doom}}'' community in order to add bits of interest to their custom levels. Among these: making floors look like water, making enemies nearly invincible, and making "voodoo dolls" of the player character whose deaths will also kill the player.
** The voodoo dolls were even used in Final Doom.
** Fans managed to hack ''Videogame/{{Wolfenstein 3D}}'' in order to design their own levels. When id Software developed ''Doom'', they specifically wrote it to be more modular and thus making custom levels much easier.
*** And then they made loading custom levels and debugging them even EASIER in ''VideoGame/{{Quake}}'' by adding a [[MasterConsole Developer's Console]] that could be opened by pressing the "~" key!
* In ''VideoGame/{{Borderlands}}'', Bloodwing won't attack if Mordecai can't see any enemies, even if they're otherwise in range. In ''VideoGame/{{Borderlands 2}}'', dialogue from Lilith indicates that Bloodwing wanted Mordecai to watch her in action.

[[/folder]]

[[folder: Four X ]]

* In ''VideoGame/{{X}}3: Reunion'', ejecting your shield generators then scooping them back up instantly recharges them. Egosoft kept it in ''X3: Terran Conflict'' because the trick is useless in combat (you have to stop maneuvering and back up in order to scoop up things you ejected from the cargo bay), and nobody wants to wait half an hour for their heavy capitals' shields to recharge on their own.
* In the ''VideoGame/{{Civilization}}'' series, the early games had an [[{{Cap}} overflow glitch]] that would cause Gandhi to suddenly become hyper-aggressive after adopting peaceful forms of government. His aggressiveness rating was supposed to drop by 2 upon adopting Democracy, but since it was already 1, it "dropped" to 255. He would usually adopt this form of government around the time that nukes became available, and would subsequently nuke other civilizations. In [[http://civilization.wikia.com/wiki/Gandhi_%28Civ5%29 later installments]], the late-game aggressiveness was removed, but Gandhi was intentionally given a fondness for nukes, which makes him a [[BadassPacifist formidable foe]] if you wait too long to go after him for your Domination victory.

[[/folder]]

[[folder: Hack And Slash ]]

* ''VideoGame/DiabloII'''s Hammerdins. Basically, Blessed Hammer is a nigh-useless spell on the non-spellcaster Paladin. Due to some bug, the Concentration aura (which should only be boosting physical attacks) boosted Blessed Hammer's damage. This created the Hammerdin, making a Blessed Hammer/Concentration combo a viable character build (with the right equipment, of course). Blizzard made sure it would continue to work properly in subsequent patches. Incidentally, this made Hammerdins into one of the strongest builds in the game (some would argue the strongest) and is a huge gamebreaker. Technically the bug was fixed in the expansion, then ''put back in'' on purpose.
* In ''{{Magicka}}'', the Teleport spell is normally only obtainable at the beginning of level 7, but it can be gotten (in multiplayer) in level 1 by laying mines at your feet and blowing yourself up and over a wall. The developers thought this was so clever they opted to leave it in.

[[/folder]]

[[folder: [=MMORPGs=] ]]

* In ''VideoGame/WorldOfWarcraft'':
** The [[http://en.wikipedia.org/wiki/Corrupted_Blood_incident Corrupted Blood incident]] later inspired an actual in-game event, the [[ZombieApocalypse Plague Outbreak]].
** In Vanilla WoW, the paladin talent Reckoning gave the paladin an extra melee attack every time he received a critical hit, stacking up to four times (i.e. at four stacks, the next melee attack the paladin perform would result in 5 simultaneous weapon swings). Originally, there was NO limit to how many times this ability could stack, resulting in a famous case where a paladin duelled a rogue 'til he'd been crit 10,000 times, then attacked and one-shot killed a World Boss. (Having to resolve 10,001 swings at once also brought the server to its knees for several seconds.) This incident became known as "the reckoning bomb." The talent was quickly nerfed, but when the Wrath of the Lich King expansion came out a few years later, it included a quest in which you fired a cannon at scourge invaders in southeast Icecrown and could occasionally shoot an enormous area-effect weapon. The name they gave the enormous area-effect weapon? "Reckoning Bomb."
** Hearthstones are devices which teleport you to your home base. They have a 10 second casting time, and taking any direct-damage ''at all'' during that time completely interrupts its use -- this was done to prevent players from using it to get out of trouble. However, until the Cataclysm expansion, the paladin's ability Divine Shield gave him total immunity to all damage for 12 seconds, allowing the paladin to use his Hearthstone uninterrupted ''even while under attack''. Since Divine Shield projected a transparent bubble around the paladin's body, this trick became known as the "Bubble Hearth." The duration of Divine Shield was reduced to 8 seconds in Cataclysm, however, taking the Bubble Hearth ability away and "fixing" this long-standing "bug" -- but this caused such an outcry among paladins that, in the subsequent Mists of Pandaria expansion, a minor paladin glyph was added to the game that cut the casting time of your Hearthstone in half while you were under the effect of Divine Shield.
** The ''Mists of Pandaria'' expansion added a glyph that allowed druids to be mounted by other players in stag form. Including... other druids in stag form, which allowed players to form [[https://www.youtube.com/watch?v=n-j71cuigtM whole stacks of stags]] standing atop one another. The bug was quickly fixed, but in a later patch Blizzard released the "Stackable Stag" item as a tribute, allowing players idle stacks of stags nearby in a similar fashion.
* The bank robbery/mayhem missions in ''[[CityOfHeroes City of Villains]]'' were originally intended to have the destructible environment scale with the player, however on initial release all the objects were unintentionally locked at fixed, low, levels. This bug became wildly popular because players now had a way of showing their characters becoming more powerful: the car that took forever to destroy at low levels disintegrated with a single attack at a higher level, and area of effect attacks caused massive destruction. The development team realized they'd accidentally hit on a good thing and have left it in.
* When swimsuits were introduced as equipment in ''PhantasyStarUniverse'', they took up all three clothing slots. A bug allowed characters to equip two layers of clothing at once, which was mostly pointless, but allowed a few would-be fashionistas to wear a swimsuit top with normal pants (or, if their character was male, go shirtless with normal pants.) A later patch made swimsuit tops, bottoms, and sandals separate items, making the mix-and-match easier.
* In ''RuneScape'', certain members-only items of clothing were made available. It was discovered that some of those items ([[http://runescape.wikia.com/wiki/Gloves_%28Canifis%29 the gloves]]) were actually usable on freeplay worlds (instead of being displayed as "member's objects" they were still wearable gloves). Because they could not be obtained on free worlds, some members would obtain them for low prices on their worlds and sell them to non-members for higher prices. They became a symbol of wealth on freeplay worlds, eventually forcing Jagex to keep it in. An extremely early example (2001 or so) would be the now taken-for-granted feature that makes items only visible to the player who dropped them for about a minute before being visible to everyone else. It was originally a bug, but after it was removed, public demand brought it back.
* Done since early development in ''[[VideoGame/{{WarhammerOnline}} Warhammer Online]]''. Since exploiting collision glitches, finding ways around an InvisibleWall, figuring out ways to survive [[NotTheFallThatKillsYou incredibly long drops]] or just discovering "holes in the world" had long been established as a hobby of MMO players, Mythic had their testing teams specifically look for these things. Instead of blocking them off in one way or another, they would instead put in little secrets and achievements. Which often involved things like [[SchmuckBait detonation plungers]] that would give you a shiny achievement badge when clicked. [[StuffBlowingUp As well as explode]] with enough force to land your corpse somewhere around the graveyard, but at least you didn't need to use your Book of Recall!
* Almost from the get go in ''GunZ'', ultimately becoming the basis for two widely popular combat styles that make use of a bug in the Sword/dagger that cancels animations, allowing for actions as simple as climbing a wall via dashing at it to multi-key combo moves. However, because of its wide acceptance by the community, many people will look down on or outright kick players who choose to play the game as it was originally intended. The developers opted to leave it in the game, as it was the cornerstone of its gameplay; it's become an official feature in ''Gunz: The Duel 2''.
* In the same vein as ''GunZ'', there's a number of techniques that have been created through player discoveries in ''VideoGame/SDGundamCapsuleFighter''. The most prominent one is [=MCA=], or "Movement Cancel Action", which allows a player to cancel out a melee dash (where if a player is far enough from an opponent when they use their weapon 1, they'll dash to them) by quickly switching to another weapon, then back to the melee weapon. This results in a unit that quickly slashes at his opponent, but denies him a knock down and, thus, can kill him with ease. This has been left in the game ever since it was discovered on the Korean servers and, when the game updated to Generation 6, added parts that allowed units to earn bonuses for performing this.
* ''VideoGame/StarTrekOnline'' had one with the duty officer assignment "Investigate Rumors of Intelligence", as in your faction's intelligence service is rumored to be infiltrating your crew. Due to the word "infiltration" being left out of the title, this led to many jokes about your faction being rumored to be intelligent. Cryptic fixed the typo, then ''put it back in'' when people complained.
[[/folder]]

[[folder: Platform Game]]
* ''Franchise/SuperMarioBros''
** Most of the NES and SNES games have slightly wonky collision detection which allows dedicated (or lucky) players to jump off walls if hit from the right angle. ''SuperMario64'' (and all of the 2D and 3D installments afterwards) canonize this as the WallJump and include puzzles or levels built around scaling two vertical surfaces.
** The MinusWorld in the original game was a programming error; however, there are many intentionally hidden stages that are unlocked via similar methods in later games.
** Not quite a gameplay mechanic, but a nod to another glitch - When Mario arrives in the Underwhere in ''VideoGame/SuperPaperMario'', a Shayde tells him that some call it "[[MinusWorld World -1]]".
** Also in ''VideoGame/SuperPaperMario'', pinning a Koopa shell against a wall and continually jumping on it would (eventually) make you ''lose points'', a nod to the classic InfiniteOneUps instance.
** Speaking of such, InfiniteOneUps were included in the ''VideoGame/NewSuperMarioBros'' games, to the point that one of the Hint Movies in ''[[VideoGame/NewSuperMarioBrosWii New Super Mario Bros. Wii]]'' shows Mario executing the technique (the World 2-3 Infinite 1-Ups video, to be exact).
** Heck, the InfiniteOneUps bug was so popular in SuperMarioBros that the designers made the glitch possible to do in the very beginning of World 1-1 in the difficult [[VideoGame/SuperMarioBrosTheLostLevels Japanese version of Super Mario Bros. 2]]
** Again, also in ''VideoGame/SuperPaperMario'', one of the Sammer Guys is named "Over the Flagpole" and talks about cheating. This is regarding a glitch in Super Mario Bros. where you... well, go over the flagpole.
** Though less of a bug and more of just an oddity, holding an item in ''VideoGame/SuperMarioWorld'' made the swimming physics change drastically, inexplicably giving the player constant forward momentum and allowing them to swim ''down'' instead of up. This was nodded to in ''VideoGame/SuperMario64'' and ''VideoGame/SuperMarioGalaxy'', as holding a Koopa shell underwater acted like an underwater jet ski and constantly propelled the player forward; in addition, ''VideoGame/NewSuperMarioBros'' lets Mario swim slightly faster if he's wearing a blue Koopa shell.
** Not particularly something added into other games per se, but the Small Fire Mario glitch from the original game is the focus of one of the later challenges in the WiiU game VideoGame/NESRemix.
* ''VideoGame/SuperMetroid'' became exceedingly well-known (and loved) for speedrunning and {{Self Imposed Challenge}}s based on [[GoodBadBugs utilizing glitches]] and [[SequenceBreaking circumventing the designers' intentions in the level design]]. In retaliation, the developers were dead sure to [[RailRoading keep the player on a fixed path]] in the sequel, ''Metroid Fusion''. This caused such an uproar among fans that, for the next game in the series, the developers slid all the way to the other end of the scale and designed the game around giving the player unprecedented freedom. ''Metroid Zero Mission'' featured: rewards for beating the game with minimal items (a classic self-imposed challenge), secret passages which allowed the skipping of "necessary" items, the ability to bomb jump and WallJump indefinitely, and the ability to use a charged shinespark in morph ball mode (based on a glitch in ''Super Metroid'' dubbed by fans as the "machball"). That isn't to say there's no sequence-breaking, period. There are a few instances in the game where you are required to have an upgrade, but through clever use of, say, the Wall Jump, you can get that item before you're supposed to. However, none of these impact the game, and are merely Missile/Power Bomb/Energy upgrades, rather than "getting the Super Missiles five bosses early."
* A large amount of ArtificialStupidity and other tricks had to be exploited to win ''Championship VideoGame/LodeRunner''. That and the difficulty of this game made it feel similar to some of the very hard ROM hacks.
* In the first ''VideoGame/ChipNDaleRescueRangers'' for the NES, on rare occasions thrown blocks would fly in a zigzag. It became a chargeable attack in the sequel.
* The Famicom Disk System version of ''VideoGame/{{Castlevania|I}}'' had a glitch that allowed Simon to keep climbing the famous staircase in the final level past where it ends. This became the route to an actual secret in ''VideoGame/CastlevaniaRondoOfBlood'' and ''VideoGame/CastlevaniaSymphonyOfTheNight''.
* In ''VideoGame/IWannaBeTheGuy'', the Kraidgeif glitch was deliberately left in, though not intentionally programmed. It ''was'' tweaked to require shot counting and perfect timing or a lot of luck.
* In ''VideoGame/{{Transformice}}'' after a player has jumped, they can not jump again until the running animation has triggered. Due to a bug, the running animation triggers if a player runs into a wall if they are also descending, thus allowing the player to jump again and climb vertical walls. The glitch was so popular that walljumping quickly became an essential part of the game, especially in the much later addition of boot camp mode.
* In ''VideoGame/{{Spelunky}}'', there is a part where to continue to the bonus levels you need to intentionally die, where you respawn inside a statue. This statue is walled off with blocks resistant to explosions, with the intended penalty being that you cannot take any items with you. This is especially problematic for [[SelfImposedChallenge Eggplant Runs]], which requires the player to carry an eggplant through the entire game and use it on the final boss - since a single player cannot take items through the statue, the intention is that multiple characters will have to carry the eggplant between them in co-op play. However, it IS possible to complete a solo eggplant run using the Ball and Chain item, a penalty item obtained by blowing up two of Kali's shrines - due to it being an obscure penalty for something most players would never do, it wasn't tested properly, and the developers forgot to mark the blocks around the statue as being immune to the Ball as well. As a result, a single player with the Ball and Chain can break the blocks around the statue, leave it, pick up the Eggplant, and go back into the statue. Since this is a lot harder than the intended way of doing it, the developers announced that they would ''not'' be patching the bug.
* Not exactly confirmed by WordOfGod, but it's very possible that the speed glitch (also called the M-speed or D-speed) in ''VideoGame/SonicUnleashed'' was reused and made into a feature in ''VideoGame/SonicGenerations'', because it was ''Unleashed'''s most famous glitch (Sega would obviously fix it), and it is very difficult to do in ''Generations'', just to honour the speedrunners.
* [[ComicBook/ArchieComicsSonicTheHedgehog Scourge the Hedgehog]]'s coloration is based on the [[http://sonic.wikia.com/wiki/Ashura "Ashura"]] [[TheMissingno glitch]] in ''VideoGame/SonicTheHedgehog2''.
[[/folder]]

[[folder: Puzzle Game ]]

* In the original ''VideoGame/{{Tetris}}'', the maneuver known as a T-Spin[[note]]A maneuver where you spin a T block into a hole without having enough space to physically do it (see [[http://www.tetrisfriends.com/help/tips_advanced.php here]])[[/note]] was a bug. It has been included as a feature in all subsequent remakes, and is considered a basic move by Tetris tournament players. It has even been expanded with "double t-spins" and "triple t-spins".
[[/folder]]

[[folder: Real Time Strategy ]]
* ''VideoGame/WarcraftII'' had a bug that allowed a player to get 100 extra lumber at the start of any game; this was so liked (due to allowing games to get going more quickly) that it became standard tournament practice to use it every game. When Blizzard remade the Battle.net version of the game, they fixed the bug but also had it start each player off with 100 extra lumber.
** Also in ''Warcraft II'' was the ability to build buildings faster by assigning workers to repair the under construction building. This was included in the sequel, but only for the human faction.
* Blizzard intends to recreate Mutalisk stacking in ''StarCraft II'', where mutalisks and other air units would be stackable given the right conditions, helping them become harder to focus down. They have acknowledged it as far back as Brood War -- rather than get rid of it, they instead added new units to each race whose '''sole purpose''' is to deal with stacked air units. It's not the only one either. They seem to have intentionally included every interface bug that ever became an element of strategy in the pro circuit, including a few parts of the dodgy unit AI.
** The way air units move in ''VideoGame/WarcraftIII'' is descended from this- the units clump together in a single [[BuffySpeak un-focus-fire-able]] formation, then explode outwards when they reach their destination ar given attack orders.
* The Salvage Corvette from ''VideoGame/{{Homeworld}}'' was only supposed to work on enemy ships that had been heavily damaged, but thanks to a programming error it ended up capable of capturing ''any'' ship. It didn't hurt gameplay balance in single-player and the multiplayer community loved it, so it was left in, though it was fixed in ''Cataclysm'' and [=HW2=] went with a different mechanic altogether.
* Many, ''many'' features in ''DefenseOfTheAncients,'' faithfully ported into ''Dota 2'' and some on them in ''HeroesOfNewerth'' as well because they are considered to increase the skill cap of the game.
** In earlier versions of [=DotA=], killing your own creeps completely denied the enemy of experience and possible gold bounty, resulting in huge experience gaps between those who knew this and those who didn't. It was changed to only deny a partial amount of experience, and ever since then denying has been a very important game mechanic.
** Manipulating creep aggro is another important laning technique. You attack an enemy hero on the other side of the creep wave so that enemy creeps aggro you instead of your allied creeps, which helps control the lane so that enemy creeps move closer to your side, near a tower, or letting melee heroes get a cleaner hit on them. Conversely, using your hero or summoned units to block incoming creeps so the creeps meet closer to your tower, allowing you to farm more easily and safely.
** Orbwalking, which is usable by heroes with autoattack enhancing skills by manually casting the skill and not toggling on auto-cast, allows users to harass enemy heroes with your autoattack without drawing creep aggro. In [=DotA=], you can move in between these skill uses, allowing you to chase more effectively while attacking.
** Creep stacking -- abusing the fact that jungle monster respawns are not triggered by them being dead, but by the absence of units in a certain area around their spawn point. Because of this, luring a jungle monster so far away from its spawn point that another one spawns in its place, then letting it walk back will duplicate the monster. Repeat to create a large pile of identical monsters which you can proceed to farm very quickly with area effect spells. An extremely important technique to increase gold flow, it was nerfed in a few ways in [=HoN=], such as reducing creep aggro time to make stacking multiple camps less viable and adding a hard limit of maximum stacked camps to 3.
** Creep pulling -- the short lane of each side is especially important, as there is a neutral camp close to the side lane where you can lure them in to, causing your creeps to aggro them until they're killed, allowing the lane to be pushed a lot further to your side and give the side lane some easy gold and experience.
** The various interactions between spells and spell block/spell immunity. Certain disables will go through magic immunity but ''activating'' magic immunity after the fact will dispel them, for instance. [=DotA=] is very finicky about what magic immunity does or doesn't block or remove, whereas it's much more straightforward in [=HoN=] (Blocks skill effects typed as Magic, and removes negative, removable status effects).
** When you specify a target destination for Blink Dagger or any Blink-type skill out of its maximum range, you blink only 80% of the maximum distance. It somewhat of a ScrappyMechanic, though; this used to be in full effect in Dota 2, but it was changed for it to work this way for Blink Dagger.
* Valve initially deemed the infamous fountain hook bug in ''{{VideoGames/Dota2}}'' (an extremely, extremely hard combo which can nearly instantly kill any hero in the game) "too hilarious to fix", but changed their mind after it was used to decide a tournament match and fixed it in the First Blood update.
* A minor example in ''LeagueOfLegends'': Initially, Lucian's passive caused his autoattack to deal bonus damage twice after he uses an ability, but if the enemy you attacked dies before the second hit, the second hit seeks another nearby enemy. The next patch, this behavior was cleaned up a bit and was made a feature.
* In ''VideoGame/{{Startopia}}'', the [[FatBastard Polvakian Gem Slugs]] have a nasty habit of getting 'stuck' inside the mud baths of the Slugpartments and dying from kidney failure. The developers caught the bug early but left it in, finding it entirely in-character for Polvakians to get too obsessed with their own comfort to care about their own well-being and essentially committing [[DeathByMaterialism suicide by luxury]]. Given the price of the Slugpartments and the level of luxury you need to attract Polvakians in the first place, the death compensation ([[{{EnergyEconomy}} 1000e]]) is a paltry sum anyway.
* "The Beach" in ''VideoGame/{{Achron}}'' is an unusual mechanical version of the PlaceBeyondTime - a gap between two "time waves" which is outside causality. Instead of removing it, the developers kept it, as it's hard to reach if you don't know the secrets and offers advanced strategic possibilities (you can use the Beach to smuggle units through hostile borders).
* ''VideoGame/DawnOfWar 2'' has the occasional physics glitch in the base game where an enemy corpse will go spiraling violently off into the stratosphere. It's most noticeable with orks. So, in later expansions Relic decided to make that a feature of how the ork psyker unit, the Wyrd Boy, always dies. It even became part of how the Wyrd Boy dies in ''VideoGame/Warhammer40000SpaceMarine''.
[[/folder]]

[[folder: Rhythm Game ]]
* The song "GAMBOL" in ''[[{{beatmania}} Beatmania IIDX]]'' has one of the easiest charts in the game; however a bizarre bug caused it to have much tighter timing windows than any other song in earlier versions of the game, making it easy to clear but extremely hard to score well on it. On Happy Sky, the bug was finally fixed: the glitched version was moved up to the Hyper difficulty, while Normal now contained a fixed version. But then on the PlayStation2 version of IIDX 11, the developers decided to troll players further by adding an Another chart; it's exactly the same as the other difficulties, except the timing windows were shrunk to the point where it's pretty much impossible to score well on it ''at all.'' Even worse, DJ Troopers' home version introduced EasterEgg codes that let players ''[[SelfImposedChallenge use the Gambol Hyper and Another timing windows on any song.]]''
* In ''[[BitTrip Bit.Trip Beat]]'', hitting the pong ball with the corners of Player 2's paddle will cause the ball to gain way too much momentum and go haywire, making the final boss trivial to beat. When the game was patched, the developers specifically didn't fix the bug because "it was a cool advanced technique".
* ''VideoGame/StepMania'' (''especially'' 3.9 and "3.95" - the version used for ''InTheGroove'' 2) had the infamous "negative BPM" bug which could be exploited to cause "warps" in a chart, which could be used for all sorts of interesting effects. The 4.0 branch unfortunately fixed this bug, but the fork sm-ssc (later merged back in as "[=StepMania=] 5") adds a new element called a "Warp" (along with "fake" arrows) which can be used for emulating this behavior in a more future-proof manner.

[[/folder]]

[[folder: Role Playing Game ]]

* ''VideoGame/FinalFantasyI'':
** "[[PeninsulaOfPowerLeveling Peninsula of Power]]", while technically a map error, was popular enough to have remained in all subsequent remakes of the game.
** Similarly, the Critical Hit Glitch. In the original NES release, each weapon had a dedicated critical hit rate in its code, but the combat engine would use the weapon's index number as the critical hit rate instead of the intended critical rate. For example, Thor's Hammer was intended to have a crit rate of 0.5%, but in practice had a crit rate of 18%. For whatever reason, the developers have chosen to keep this error in all remakes of the game.
* There is some [[EpilepticTrees fan speculation]] that the Franchise/{{Pokemon}} Deoxys may be based on [[TheMissingno Missingno]]. The [[GlassCannon ridiculously high Attack and ridiculously low Defense]] of its Normal Form would appear to corroborate this, but there has been no official word on whether or not this is the case. Considering that the (intentionally placed) Generation III glitch Pokémon have the exact same stats as Deoxys, this theory is fairly plausible.
** Also, in [[VideoGame/PokemonRedAndBlue Red and Blue]], there was a truck found only when surfing before the S.S. Anne had set sail. Like nearly everything else in the first-gen games, the fact that it existed at all yet didn't do anything immediately apparent made players make up all sorts of crazy rumors about how to get Mew and other unknown Pokemon from it. Players could get to it through a glitch or by losing to a trainer after receiving Cut so that the ship wouldn't leave[[note]]you need Surf to get to the truck, under normal circumstances by the time you have Surf the ship is long gone and you can't even go back into its dock[[/note]]. The truck returned in the remakes, and if you managed to get to it you could find a Lava Cookie nearby.
** Yet another (potential) glitch reference. In Red/Blue/Yellow, the Pokedex number for 'M (likely the second-most-known glitch Pokemon) is "000". Fast forward several years later to Black/White, and Victini's Unova Dex number is "000".
** The pokemon, Spiritomb, is infamously hard to obtain, requiring you perform a very specific sequence of events: first, obtain an Odd Keystone and place it in the Hallowed Tower; next, talk to online [=PCs=] ([=NPCs=] don't count) in the Undergroud area at least 32 times; then, return to the Hallowed Tower and look in it, to fight a Level 25 Spiritomb - a Ghost/Dark-type pokemon that had no weaknesses (until Gen VI) and moderate stats. This is likely a reference to the old urban myths of oddly-specific sequences in the Red and Blue/Green games that would yield a mythical "Pokegod" to whomever performed them correctly.
*** Gen IV is rife with such references to these rituals: In order to obtain either Glaceon or Leafeon, the player's Eevee needs to level up when the player is in the same area as specific special stones (only two of these stones exist in the game).
*** Another Pokemon, Feebas, is located in EXACTLY 6 spaces on Route 119 in Ruby/Sapphire/Emerald. And those spaces are decided RANDOMLY every time you start the game, the day changes, or when you enter the area. Needless to say, trying to find those spaces is maddening. This was made worse in Generation IV when they downed the number to FOUR in Mt. Coronet, and required you use a Super Rod. It's as useless as Magikarp, and rather than simply evolving upon hitting a certain Level such as its more-famous cousin, Feebas's "Beauty" Stat (in Gen III only) must be sufficiently high when traded (future games simplified this by requiring it to be holding a specific item when traded), in order to obtain a legitimately-powerful pokemon, Milotic. This is, of course, a reference to the myriad "hidden" Pokemon that purportedly required very specific rituals be performed and then traded under certain conditions in order to be obtained from way back in the days of Red/Blue/Green/Yellow.
** There were a pair of Pokemon cards from early in the TCG, "Flying Pikachu" and "Surfing Pikachu". Obviously, neither Fly nor Surf could be learned by the famous Electric Mouse Pokemon... until Pokemon Stadium allowed the player to obtain a Surfing Pikachu, and Pokemon Yellow included a mini-game which could only be played if you had a Pikachu which Surfed. While it has never been possible to teach or breed a Pikachu with either Surf or Fly, both moves are a legal part of its moveset, and Surfing Pikachu and Flying Pikachu are a now common Promos in the video game. In Pokemon Heart Gold/Soul Silver, a event for the game's gadget allowed you to go to the Pikachu Forest, allowing to capture Pikachu with Surf, Fly, or both.
* ''VideoGame/FinalFantasyVI'' is an interesting case. The well-known Vanish-Doom/X-Zone exploit wasn't fixed in the PSX port -- but the programmers DID change one boss to be invulnerable to Vanish (Phunbaba), sort of turning it legit for other bosses. (That said, Phunbaba could crash the game when being Vanish-Doomed, and they didn't even get the "invulnerable to vanish" part quite right.) However, the Game Boy Advance version of the game ''thoroughly'' squashed Vanish-Death/Banish (as the instant-death spells were retranslated), at least on anything immune to Death/Banish under normal circumstances.
* In ''VideoGame/SuperRobotWars'', all other music being [[InterruptingMeme overrid-]] '''''[[http://www.youtube.com/watch?v=ot-0-KyPd0Y TROMBE!]]'''''
** To explain this in greater detail, whenever Elzam Branstein would use an attack or do something that triggered his theme in the first game he appeared in, his theme would override anything that was playing in the background, even final boss music. The fandom found this hilarious, due in no small part to his theme being awesome, and Banpresto has deliberately included it in every SRW game where he appears since. It even overrides [[Anime/NeonGenesisEvangelion Komm, susser tod]] in the End of Evangelion route from ''Alpha 3''.[[note]]To explain the ''why'' in greater detail, Elzam is initially fought as a boss, where his theme has higher priority than the player characters' themes. Due to a glitch, when he later joins you, player theme priority is ''added'' to his boss priority, rather than ''overriding'' it, making his theme override pretty much every other music track in the game.[[/note]]
** It ''doesn't'', however, override SourceMusic, such as ''The Beautiful Blue Danube'' being blasted from a [[GoShogun battleship's speaker system]], or the protagonist of ''{{Macross 7}}'' performing a literal AutobotsRockOut session. Somehow, this just makes it more awesome.
* Smith is a talking horse in the main ''Franchise/{{Ultima}}'' series and ''Ultima: Worlds of Adventure 2: Martian Dreams''. Originally, Smith was included in ''VideoGame/UltimaIV: Quest of the Avatar'' and was to give a clue on how to beat that game, but the programmers forgot to add it into his conversation tree. In ''VideoGame/UltimaV: Warriors of Destiny'', Smith was given back his full dialogue and, up to ''VideoGame/UltimaVIIPartII: Serpent Isle'' (where he almost gives a clue about the actual game), Smith has been giving out clues in the form of untimely information -- he tells the player what they should have done to have beaten the ''previous'' game, not the ''current'' one.
* A very interesting pseudo-example in ''VideoGame/BaldursGate'': Whenever a key character in the first game was missing from a scene (which could happen because of glitches), they'd be automatically replaced by a debug character called "Biff the Understudy". In ''Baldur's Gate II'', Biff became an actual character with his own subplot.
* In the original Super Famicom version of ''VideoGame/FinalFantasyVI'', a bug rendered any item as being equippable as a helmet, with Edgar's [[ThisIsADrill drill]] tool being the best option. ''DissidiaFinalFantasy'', already rife with {{Mythology Gag}}s, saw fit to include a drill as being the headset equip for the 'Machine' equipment set.
* In ''ImprobableIsland'', at the start of a new day it gives you a message saying. "It is a new day! Strap your to your back and head out for adventure!", but if you had no weapon it would just be fists instead. This was removed in one update, but quickly put back in due to popular demand. It now appears on the [[http://merch.improbableisland.com merchandise]].
* ''VideoGame/TheElderScrollsVSkyrim'' has a few physics quirks, one of which causes a player, companion, or random target to fly hundreds of feet into the air after being hit with with a Giant's club... in classic [[BlownAcrossTheRoom Blown Across The Room fashion]]. Though unintended, designers decided not to patch it due to its popularity with players.
** In "Fall of The Space Core", a semi-official mod that Valve made to commemorate the opening of the Skyrim Steam Workshop, the Space Core can be returned back to space by being within the impact radius of a giant's club swing. It screams "SPAAAAAAAAAAAACE" on the way back up.
** Basically any bug or glitch that [[GoodBadBug isn't game-breaking]] is allowed to stay as long as it's funny (e.g. putting a bucket on somebody's head so they can't see you robbing them blind). The crime-reporting-chickens bug that cropped up during development didn't qualify mainly because it would be unfair to players who didn't know about it.
* A glitch in the Paragon resolution of the [[LoonyFan Conrad Verner]] side quest in ''VideoGame/MassEffect1'' (where Shepard gently talks Verner into going home) causes the OldSaveBonus for ''VideoGame/MassEffect2'' to assume you went with the Renegade resolution (where Shepard threatens Verner into giving up on becoming a Spectre)[[labelnote:*]]The glitch is that both the Paragon and Renegade options are ticked in the data, and the game checks for the Renegade option first.[[/labelnote]]. In ''VideoGame/MassEffect3'', you can encounter Verner on the Citadel, where he apologizes to Paragon Shepard for claiming they threatened him with a gun--he was under a lot of stress.
* In the ''VideoGame/{{Fallout}}'' series, players quickly learned that you wouldn't get blamed for killing someone if you [[GrenadeTag reverse-pickpocketed a live grenade]] onto them; in ''VideoGame/{{Fallout 2}}'', this was an easy way to get rid of those annoying child pickpockets in the Den without getting the [[MoralEventHorizon Childkiller]] perk. Future installments canonized this as a game tactic; ''VideoGame/{{Fallout 3}}'' gives you an achievement for doing it, and the ShowWithinAShow calls it "the ol' Shady Sands Shuffle."
* It's possible that the "Mime" job class introduced in ''VideoGame/FinalFantasyV'' was based on a fun glitch in ''VideoGame/FinalFantasyIV'' that caused Kain to copy the previous character's actions in battle.


[[/folder]]

[[folder: Shoot Em Up ]]

* Anyone who has ever played ''VideoGame/SpaceInvaders'' will recall that the enemy ships slowly speed up as you destroy more of them. This was due to an oversight by the original programmer - the presence of so many sprites loaded down the processor, slowing the game down considerably. As the ships were destroyed, the game had less processing to do, so it ran faster. He liked it so much that he left it in, and every ''Space Invaders'' game since has done the same. The significance of this oversight extends further than merely subsequent Space Invaders games -- it introduced the entire concept of difficulty curves to video games.
* The egregiously NintendoHard ''VideoGame/{{Gradius}} III AC'' had significant slowdown when there was a lot of enemies/bullets on the screen, which was practically required to navigate these bullet storms. The PS2 CompilationRerelease even had an option to emulate the lag/slowdown. Similar to the ''Street Fighter II'' and ''Space Invaders'' examples, this would influence other games, as intentional, hardcoded slowdown when bullet density reaches a certain point has become a widespread feature in BulletHell games.
* The arcade version of ''[[VideoGame/DonPachi DoDonPachi Saidaioujou]]'' had a glitch where if your combo bonus exceeded [[PowersOfTwoMinusOne (2^31 - 1)]]/100, it would turn into 999,999,999 because the programmers correctly detected the overflow but used 32-bit fixed-point signed integers instead of 64-bit ones in the intermediate calculations. This would then send your score through the roof. When the game was ported to Xbox 360, the glitch was fixed, but Arcade HD Mode contains an option to restore the original glitched behavior.
* The PC-98 ''Videogame/{{Touhou}}'' games had a glitch where using a bomb ''very'' shortly after getting hit would cause you to not die. The Windows games intentionally coded this in, and gave it a more reasonable window for using.

[[/folder]]

[[folder: Simulation Game ]]

* ''{{VideoGame/Patrician}} III'' and its predecessor Patrician II are known to have many bugs and exploits thanks to its long-running community, but one of them qualifies as this trope as it gave way to the practice-extensive [[http://www.patrizier-forum.de/index.php?page=Thread&postID=19583 Turkish Building Technique]] which has been considered as the ultimate supreme discipline of the game ever since. And while ''Patrician IV'' got rid of street-free construction, it has kind of a sister glitch that [[http://www.patrizier-forum.de/index.php?page=Thread&postID=67624 enables you to build outside the maximal city wall]].
* In the original ''VideoGame/ZooTycoon'' game, there was a rather odd glitch in which an emperor penguin in a proper exhibit (for penguins anyway) would kill any other non-penguin herbivore added to said exhibit. In the sequel, however, this is fixed; messing too much in the genetic lab minigame that comes with an expansion pack will result in a psychotic rockhopper penguin with teeth, red glowing eyes and a taste for dinosaur meat. Placing any other animal (or a particularly annoying guest) in the same exhibit as the creature will result in an untimely demise, even a T-Rex. And you can't sell it. EVER. If someone offers you a penguin to adopt DON'T accept!

[[/folder]]

[[folder: Sports Game ]]

* In ''Tiger Woods PGA Tour '08'', there was a glitch nicknamed the "Jesus shot" which meant that in the right conditions, a ball hit into the water could still be played, complete with the golfer walking on water to hit it. Prior to the release of the 2009 edition, EA responded with a [[http://www.youtube.com/watch?v=FZ1st1Vw2kY live-action recreation]] of the shot, claiming "It's not a glitch. He's just that good." Then, in the 2010 edition, the first bonus challenge was to recreate the scene, earning the achievement "Levinator25", named after the person who discovered the glitch.

[[/folder]]

[[folder: Third Person Shooter ]]

* ''SuperMondayNightCombat'' has Rampage Jumping. One of the playable characters, Cheston, is capable of activating a skill that caused him to pound the ground in mid-air, causing him to rocket forward quickly. The developers liked it enough that instead of removing the glitch, they added additional skill drain when [=RJing=] to balance it out. A similar physics glitch results in incredibly fast movement speeds when moving off of ledges, over jump pads, or even using mobility skills in mid-air. Consequently, the old "low mobility" label on Enforcers was removed, since only the Gunner at the time really lacked a way to zoom across the arena.

[[/folder]]

[[folder: Wide Open Sandbox ]]

* ''{{Crackdown}}:''
** Sported an Agency SUV which could not only jump with super-hydraulics at the highest level, but also drive up walls. According to the dev team, this function was created completely by accident, but was left in the final game since it wasn't truly a gamebreaker.
** The DLC ExpansionPack includes a Dune Buggy that is especially designed for wallclimbing.
* ''{{Roblox}}'' had a glitch in 2008 where you can wear 2 or 3 hats at once. It was eventually made a feature.
* In ''{{Minecraft}}'':
** The [[ActionBomb creeper]]'s model was that of a failed pig model. The model failed due to Notch attempting to make the pig model longer horizontally, but he botched the coding and it made the model grow longer vertically instead, which also made the legs look weird in that position. Notch liked how creepy it looked and dubbed it the Creeper.
** When the pistons were added, people soon realized that they sometimes got stuck in an incorrect state and need to be "updated" to make then snap back to their expected state. Ingenious people managed to transform this glitch into so-called block update detectors that significantly expanded the the ways redstone mechanisms can interact with the rest of the game world. Another, unrelated glitch with the pistons made it possible to propagate redstone signals arbitrarily far within a single tick (0.1s). This enabled the players to circumvent the intended 150m/s limit. This later capacity will be expanded in the next update, making it significantly easier to transmit instantly both edges of the signal.
* The PC game ''{{Spore}}'' includes some glitches that have been left in, such as the ability to create invisible limbs and therefore make parts on the created creature float in midair. Another glitch made it possible to create asymmetrical creatures, and a later patch upgraded this to an actual feature, with a simple keybind (''A'' to be exact) to get the previously tedious effect. Though, asymmetrical ships, vehicles and outfits tend to look better than creatures themselves.
* An update added the Captain's Quarters to ''EveOnline'', which include various virtual screens bombarding one's avatar with videos. Some nifty people located these videos in the game folder and fiddled with them a bit, to change them to videos they liked. [[http://www.eveonline.com/en/incarna/article/2432/you-just-won-a-brand-new-flat-screen-tv-ready-for-pickup-in Recently, CCP made it very easy to do so without needing to change any of the game data.]]
* The entire ''VideoGame/GrandTheftAuto'' franchise is one. It started life as a pretty normal racing simulator with police who pull over racers. However, the AI for the police was far too aggressive and started slamming into racers. Playtesters had much more fun dueling with the police than doing the racing, so the developers made that a core gameplay component. And a franchise was born.
* While developing necromancy for ''VideoGame/DwarfFortress'', Toady accidentally created undead from the skin and hair of a killed monster, as well as its skeleton. He figured it made as much sense as skeletons and zombies, and kept it. Nowadays undead skins and hair are among the most dangerous of all DF creatures, since they have no vitals, don't need to breathe, and don't bleed out from massive damage-- short of [[DroppedABridgeOnHim cave-in, atom-smasher]], or encasing in ice/obsidian, they ''can't be killed''.
** In one update, he fixed the "glitch" that meals made entirely of booze would melt below room temperature, rather than the glitch that lets you make meals out of booze.

[[/folder]]

!!Non-video game examples:
* There's a web-enabled tool for creating fonts called [[http://fontstruct.com/ Fontstruct]]. There was a glitch that enabled you to stack bricks you use to create fonts. In a recent update they made it an actual feature.
* Traditional automatic transmissions using a fluid coupling and planetary gearset "creep" when in gear and not held against the brake. Continuously variable and dual-clutch automated manual transmissions don't have to, but are designed to anyway since that's [[CoconutEffect what drivers expect]] in a two-pedal transmission system.
** Designers have learned that without the precise low speed control from this creep or from feathering the clutch on a manual, a car becomes almost impossible to park. Even electric cars have added a creep feature despite having direct drive systems and the ability to turn power on and off at any time.
* A glitch on the adoptables site Website/UniCreatures replaced the sprite for Flarius (a standard fire-breathing dragon) with that of Caprine (a goat). Shortly afterwards, the mods released a new creature: the [[MixAndMatchCritters goat-dragon]] Capricious.
* Serious example with costly consequences: during the dark ages of early CPU designs, some [=CPUs=] either wouldn't do what they were supposed to do when fed certain instructions, or yielded completely unexpected results. This in turn forced OS programmers to anticipate those glitches to make ''their'' side of things work as designed. This phenomenon came full circle when the CPU designers were later forced to incorporate the bugs of the early [=CPUs=] just so those dubious [=OSs=] would work properly. [[ViciousCycle And so on and so forth.]] This has been one of the reasons why the x86 instruction set (used by Intel, AMD, and others) is so ludicrously huge; it contains tons and tons of Ascended Glitches.
* It doesn't stop with the {{metagame}} between CPU designer and OS programmers. Suppose you have a huge set of data stored in [[TheAllegedCar an obscure and outdated system]], the kind that has been out of production for more than a decade. You want to retrieve that data to store in a shiny new system. So you grab an instruction manual and build an emulator [[ShapedLikeItself to emulate]] the environment in which the system used to run. When you actually run it, the old system promptly crashes and lets out a strange-smelling puff of smoke (which is probably your data). Why? It's because the programmers of the old system didn't actually build their things according to the reference manual but to the behavior of the real boards-and-cables environment they had in hand. No wonder the system choked inside your environment.
* This was one of the main reasons why Windows Vista had so many problems with older software being incompatible. Vista cleaned out a lot of the bugs and glitches from previous iterations of Windows, which may have sounded great on paper but a lot of Windows software had been built around those bugs and glitches. Most notably, Vista no longer automatically gave administrative rights to every user account -- something that many programs had taken for granted on XP and earlier versions of Windows. A lot of software needed to be patched to account for these changes.
* Just before the filming of the first regeneration on ''Series/DoctorWho'', it was discovered that a vision mixing desk was faulty in such a way that adjusting a specific control would overexpose the image. This was seized upon to create the iconic shot of William Hartnell's face dissolving into Patrick Troughton's, and by doing so, influence the visual look of almost all the other regenerations. (Originally, the intention had been to have the Doctor collapse with his cloak over his face, and just pull it back to reveal he'd turned into Troughton.)
* The early electro-mechanical {{Pinball}} game ''Pinball/{{Contact}}'' did not include a noisemaker of any kind. As a joke at Pacific Amusement, one of the employees wired a doorbell buzzer to the Contact Switch on a demo table -- every time it was hit, owner Fred [=McClellan=] thought his phone was ringing and tried to answer it. When the bell proved to be an attention-getting device, it was added to all subsequent machines.
* In ''MyLittlePonyFriendshipIsMagic,'' Scootaloo and Sweetie Belle were animated as students in a classroom at the beginning of the episode where Apple Bloom will first meet them in a party at the ''end.'' As it didn't make sense for her to not know who they were if they were classmates of hers, a hasty repaint (and a bow-and-arrow cutie mark added to one) turns them into Archer and Sun Glimmer. Archer went on to be a background character in another episode and even appear in the Gameloft mobile game; once a quick edit to hide a continuity gaffe, she's become a ''real character'' now. No one's sure why Sun Glimmer has had no such luck.
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