When a Good Bad Bug is particularly liked by fans of a game (more than just the God Modders), sometimes something interesting happens.
This is when a glitch is upgraded to the status of a legitimate gameplay mechanic or 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. However, some of these aren't actually glitches, they're exploits.
Of course, bugs that break the game balance usually aren't eligible for this, unless the game is rebalanced to accommodate them. Game Breaking Bugs are never eligible, of course, owing to making the game unwinnable. note Well, maybe a minor one could be eligible, if you want to make a level/your game Nintendo Hard. No-one likes those bugs.
Good Bad Bugs, where glitches can be used for gaining an advantage of the game or just pure entertainment.
Ascended Meme, where those related to the source material of the meme recognize it.
Jurassic Park The Game 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.
In the original The Legend of Zelda, players can quickly change the direction Link's facing while stabbing with the sword to attack in multiple directions. It's possible the spin attack, first appearing in A Link to the Past and having gone on to become a series staple, is based on this trick.
In The Legend of Zelda: Link's Awakening, there was an Easter Egg where assigning bombs and arrows to your buttons and pressing both at once allowed you to fire a bomb attached to an arrow. While not necessary at any point in Link's Awakening's main quest, Bomb Arrows became an official game mechanic in Twilight Princess.
The 3DS version of The Legend of Zelda: Ocarina of Time 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.
The combat system in Devil May Cry was born from a glitch that was removed during the development of 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 so cool that Capcom decided to get some ideas from it.
In the NES game Ninja Gaiden, 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.
During a phase in which thatgamecompany had trouble getting the ending levels of Journey to properly resonate with playtesters, one test ended prematurely when a glitch caused the game to seem like it was over 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.
Combos, which would become a cornerstone mechanic of not just the Street Fighter 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 Word of God) 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 Word of God statements to the same effect), players 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 Vs. games (transforming into Ken or Akuma, invisible/explosive/multi-hadoken) are inspired by glitches or modifications created for a pirated edition of the original Street Fighter II'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 SF 2 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.
Just about every advanced tactic used in competitive Marvel vs. Capcom 2 play is a glitch or caused by a glitch.
Similarly, roll cancelingnote Inputting a roll quickly followed by a special move gives the special move invincibility for whatever the duration of roll would have been. in 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 Shout-Out to a glitch from Final Fight 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 The King of Fighters 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 Wild Mass Guessing 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.
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 Dummied Out of the arcade version of Mortal Kombat 4, but made unlockable (although he lacked fatalities) in the console versions, and had a couple of rather glitchy alternate costumes.
Even though Nintendo painstakingly went out of their way to erase any traces of it in Brawl, Wavedashing is so beloved among the Super Smash Bros. fandom that fan projects such as Project M and Super Smash Bros Crusade have taken a lot of trouble to recreate it from scratch.
First Person Shooter
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 Quake III: Arena, so a new patch featured it as... well... a 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 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 "Rocket Jump". 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 Quake II, 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 iddid have some knowledge of this technique in mind when designing the game.
The Expansion PackQuake II: 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.
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".
Team Fortress 2'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 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.
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.
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 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 launchersnote 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, forcing playtesters to guide missiles 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 Desperation Attack near the end of the battle.
One sequence in Left 4 Dead 2 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 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 Tribes: Vengeance's campaign.
Lampshaded by thisApril Fools' Day 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.
Halo: Combat Evolved 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 Red vs. Blue), 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 Halo 2 and 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 Halo: Reach 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 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 Wolfenstein 3D in order to design their own levels. When id Software developed Doom, they specifically wrote it to be more modular and thus make custom levels much easier.
In X3: 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 Civilization series, the early games had an 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 later instalments, the late-game aggressiveness was removed, but Gandhi was intentionally given a fondness for nukes, which makes him a formidable foe if you wait too long to go after him for your Domination victory.
Hack And Slash
Diablo II's Hammerdins. Basically, Blessed Hammer is a nigh-useless spell on the non-spellcaster Paladin. Due to some bug, Blessed Hammer's damage was boosted by the Concentration aura (which should only be boosting physical attacks). 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.
In Vanilla World of Warcraft, 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 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 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 Phantasy Star Universe, 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 (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 Warhammer Online. Since exploiting collision glitches, finding ways around an Invisible Wall, figuring out ways to survive 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 detonation plungers that would give you a shiny achievement badge when clicked. 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 SD Gundam Capsule Fighter. 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.
Star Trek Online had one with the duty officer assignment "Investigate Rumors of <your faction> 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.
Reportedly, the blocks that release multiple coins when hit multiple times were actually due to a programming mistake. After fixing the blocks, the designers decided they missed them and deliberately programmed them back in, and they've been mainstays in the series ever since.
Most of the NES and SNES Mario games have slightly wonky collision detection which allows dedicated (or lucky) players to jump off walls if hit from the right angle. Super Mario 64 (and all of the 2D and 3D installments afterwards) canonize this as the Wall Jump and include puzzles or levels built around scaling two vertical surfaces.
The Minus World 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 Super Paper Mario, a Shayde tells him that some call it "World -1".
Also in Super Paper Mario, pinning a Koopa shell against a wall and continually jumping on it would (eventually) make you lose points, a nod to the classic Infinite 1-Ups instance.
Again, also in Super Paper Mario, 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 Super Mario World 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 Super Mario 64 and Super Mario Galaxy, as holding a Koopa shell underwater acted like an underwater jet ski and constantly propelled the player forward; in addition, New Super Mario Bros. lets Mario swim slightly faster if he's wearing a blue Koopa shell.
The Double Mario ability in Super Mario 3D World, which allows Mario to clone himself, was left in after a developer accidentally placed 2 Marios in a level using the level editor.
Super Metroid became exceedingly well-known (and loved) for speedrunning and Self Imposed Challenges based on utilizing glitches and circumventing the designers' intentions in the level design. In retaliation, the developers were dead sure to 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 Wall Jump 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 "mockball"). 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 Artificial Stupidity and other tricks had to be exploited to win Championship Lode Runner. That and the difficulty of this game made it feel similar to some of the very hard ROM hacks.
In the first Chip 'n Dale Rescue Rangers for the NES, on rare occasions thrown blocks would fly in a zigzag. It became a chargeable attack in the sequel.
In I Wanna Be the Guy, 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 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 the original Tetris, the maneuver known as a T-Spinnote A maneuver where you spin a T block into a hole without having enough space to physically do it (see here) 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".
The first game of the Puzzle League series, Panel de Pon/Tetris Attack!, had a few bugs that added to rather than detracted from the tactical depth of the game. Due to the game's cult following and highly technical nature, later releases that recoded the engine manually added these bugs as normal gameplay features. Now, the series' lesson mode even teaches the player how to use them.
Real Time Strategy
Warcraft II 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 Salvage Corvette from 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.
When you specify a target destination for Blink Dagger that is out of range, you will blink only 80% of the maximum distance. There is no range indicator in the UI.
Killing your own creeps to deny experience and money to the enemy.
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.
Orbwalking, a form of animation cancelling that enables one to shoot while moving, only for heroes with abilities that enhance one's normal attack. Also, these abilities can be cast manually and will act as a spell instead of an auto attack, not drawing creep aggro for one.
You can give an attack order to an enemy at the opposite side of the map and it will aggro nearby enemy lane creeps so they attack you instead of your lane creeps, which helps push the lane a little bit without stealing last hits and money from the carry.
Conversely, you can use your hero and other controllable units to block incoming creeps so they meet the enemy creeps closer to your tower, enabling you to farm more easily.
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.
In Startopia, the 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 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 (1000e) is a paltry sum anyway.
The song "GAMBOL" in 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 PlayStation 2 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 Easter Egg codes that let players use the Gambol Hyper and Another timing windows on any song.
In 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".
StepMania (especially 3.9 and "3.95" - the version used for In The Groove 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.
"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.
Also, in 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 leavenote 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. 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".
Final Fantasy VI 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.
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 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.
Smith is a talking horse in the main Ultima series and Ultima: Worlds of Adventure 2: Martian Dreams. Originally, Smith was included in Ultima IV: 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 Ultima V: Warriors of Destiny, Smith was given back his full dialogue and, up to Ultima VII Part II: 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 Baldur's Gate: 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 Final Fantasy VI, a bug rendered any item as being equippable as a helmet, with Edgar's drill tool being the best option. Dissidia: Final Fantasy, already rife with Mythology Gags, saw fit to include a drill as being the headset equip for the 'Machine' equipment set.
In Improbable Island, at the start of a new day it gives you a message saying. "It is a new day! Strap your <weapon> 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 merchandise.
The Elder Scrolls V: Skyrim 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 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 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 Conrad Verner side quest in Mass Effect 1 (where Shepard gently talks Verner into going home) causes the Old Save Bonus for Mass Effect 2 to assume you went with the Renegade resolution (where Shepard threatens Verner into giving up on becoming a Spectre)* The glitch is that both the Paragon and Renegade options are ticked in the data, and the game checks for the Renegade option first.. In Mass Effect 3, 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 Fallout series, players quickly learned that you wouldn't get blamed for killing someone if you reverse-pickpocketed a live grenade onto them; in Fallout 2, this was an easy way to get rid of those annoying child pickpockets in the Den without getting the Childkiller perk. Future installments canonized this as a game tactic; Fallout 3 gives you an achievement for doing it, and the Show Within a Show calls it "the ol' Shady Sands Shuffle."
It's possible that the "Mime" job class introduced in Final Fantasy V was based on a fun glitch in Final Fantasy IV that caused Kain to copy the previous character's actions in battle.
Shoot Em Up
Anyone who has ever played Space Invaders 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 Nintendo HardGradius 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 PS2Compilation Re-release 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 Bullet Hell games.
The arcade version of DoDonPachi Saidaioujou had a glitch where if your combo bonus exceeded (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 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.
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 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 enables you to build outside the maximal city wall.
In the original Zoo Tycoon 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!
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 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.
Third Person Shooter
Super Monday Night Combat 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.
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 Expansion Pack 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.
The creeper's model was that of a failed pig model. Oh how far they've come.
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.
The entire Grand Theft Auto 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 Dwarf Fortress, 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 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.
Non-video game examples:
There's a web-enabled tool for creating fonts called 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 what drivers expect in a two-pedal transmission system.
A glitch on the adoptables site Uni Creatures 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 goat-dragon Capricious.
In Wreck-It Ralph, Vanellope's ability to teleport short distances due to her glitchy programming makes her the most popular racer in Sugar Rush. It may even be that, after her debut, her ability to teleport is perceived as a power of hers, rather than a glitch. The players can be seen deliberately activating the teleport with a button sequence, so it probably was a special technique, reflecting her unique status. Turbo would have convinced the other characters, or even Vanellope herself, that it was a glitch to keep her from racing. In other words; invoked and inverted.
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. 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 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 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 (though not without unleashing a ton of new ones), 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.
In Justice League of America 51, Green Lantern mentions fighting the "Warlock in Dis". This turns out to be a hint for a confrontation with the Warlock of YS in a future issue.
Older Than They Think: Just before the filming of the first regeneration on Doctor Who, 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.)