Good Bad Bugs/Video Games/Wide Open Sandbox

Examples of in  games include:

Dwarf Fortress
It's probably safe to say that various bugs and exploits are half the fun of the game. See more on its own page. "ToadyOne: "I think I made the fish too hardcore.""
 * Mad Hammerer, one of the author's favorite bugs. A Hammerer carries out death sentences by striking the prisoner with a hammer. If unable to wield a hammer (due to both arms being broken, for example), he would instead bite the subject to death and walk around with the man's bitten-off limbs in his mouth forever, until they start to rot.
 * Toady's other favorite bug involved a farmer walking to a furniture stockpile, picking up a bed, then walking to a farm plot and planting the bed as if it were a seed.
 * Other bugs that tend to be mentioned nostalgically: infinite magma floods, serial killer elephants, the dwarves' utter indifference to being on fire. Note that all of these were part of the legendary Boatmurdered.
 * The "on fire" bug becomes particularly dangerous/hilarious when combined with a fortress's highly-flammable booze stockpile. Which dwarves regularly visit for a drink... moreso if extreme heat (from, say, fire) is making them thirsty... It also may have been one of the reasons to invent the Decontamination Chambers.
 * You can also start your fortress at an existing settlement. Its inhabitant will not be listed as your citizens, but as "friendly".
 * Take a human town... then proceed to undermine their buildings, causing them to collapse, and raid the rubble for fortress materials. Where this enters Good Bad Bug territory is the fact that the humans don't care, and you can massacre their population, destroy their city, and steal the shattered remnants of their belongings without their losing the "Friendly" status.
 * Yay, pet kobold village! Mostly, this just gives the player more to mess with/protect in locations that aren't ridiculously lethal. Also, traps did for a while hit "Friendly" creatures, which was a problem - for pets, foreign diplomats and incoming migrants... but not kobolds with their [TRAPAVOID] tag.
 * The absurdly overpowered throwing. A character can mangle a body part and brutalize enemies internal organs with a pebble, a coin, or even vomit. Throwing eventually was nerfed, but now you can pinch people's heads off.
 * They can also bash enemies to death with their own pants, or fell someone with a well-thrown sock.
 * "Tamed" animals that have killed dwarves in past...aren't. They spend their time gleefully slaughtering the hairy ones, who still believe them to be tamed. The main way to stop this is to order the critter butchered as soon as you tame it, which gets you a lot of raw materials if it's something like a dragon or titan.
 * There were also (sadly removed) bugs involving individuals ordering someone to hurt them - fortress mayors sentencing themselves to be beaten when their own mandates failed, and assorted folk in Adventure Mode requesting their own assassinations.
 * The carp. Sweet Armok, the carp.... A bug in the skill system meant anyone could buff up their stats by swimming. Seeing as they do that all the time, the carp became invincible monsters.


 * While the carp have stepped down, Giant sponges have taken up their mantle. Since the engine can't handle an unmoving animal properly and has some issues with determining the death of creatures without body parts or blood, they are immune to pretty much anything other than instant-death effects and can slowly grind to pulp any non-flyers that dare to approach them (whether your dwarves or incoming Legions Of Zombies).
 * You can make magma-powered smelters out of ice.
 * Similarly, constructions of any type are completely invulnerable. Not only does this allow you to hold magma back with ice walls and wait out a forest fire inside a wooden building, it also means that a rampaging hellbeast that can smash whatever doors, floodgates, and bridges you put in its way will be stopped dead by a wall made of glass.
 * "Planepacked" bug (fixed). The artifacts can be decorated with images of themselves, which normally was quite rare, but another bug kept the maker add more and more materials for decoration, and in right conditions will get recursive sooner or later.
 * In the initial builds of the 2010 version, it was possible for animals and dwarfs to melt in the rain. What happened was that Dwarfs got covered in water and high temperatures will heat this water. This then caused the dwarf's fat (whose melting temperature was much lower than it should be) to melt off. Naturally, this being Dwarf Fortress, this was soon put to good use.
 * A typical fort in the 31.10 version is less than 200 Z-levels tall. The ultimate metal, adamantine, is only found deep underground. An erratic bug in world generation resulted in a location having a 2200+ Z-level tower of adamantine shooting into the sky. Forum Thread
 * Nothing exists off the edge of the map. You can't dig out the edge squares, but you can carve them into fortifications and use them as an infinite sink for water (or magma).
 * Certain powerful enemies are rampant building destroyers, taking out floor hatches, floodgates, workshops, and anything else they can get their appendages on. If a door they'd like to wreck is jammed open, they will politely wait for it to close before doing anything at all.
 * The danger room, where military dwarves are stuck in a room with training spears used in an upright spear trap hooked to a repeater. The spears are unable to actually hurt the armored dwarves but quickly give massive boosts to blocking and dodging as well as lesser boosts to weapons and armor skills.
 * A few materials, notably lignite and graphite, have an ignition point but no melting point. Thanks to this and a quirk in the way items in containers are tracked, if you put some in a bin and light it on fire, it never goes out. You can drain an entire ocean into a bin full of burning lignite.
 * If pieces of wall/floor fall into liquid due to a cave in, liquid displacement is simulated by vertically teleporting the displaced liquid to the nearest empty space. Players have taken advantage of this to create the "magma piston": a hundred level (or more) high stone column carved out of the earth and made to fall into a pool of magma, causing the magma to teleport up a hundred levels.
 * This, along with bugs like the ability to store an infinite amount of stone on one square if you mark it as a dump site, is such a savings in time, energy, and not-killing-your-frame-rate that some players don't even consider it an exploit. The introduction of minecarts cut down on this, however - these allow to both transport magma and store bulky items compactly (as well as many other tasks) in more straightforward, controllable and entertaining ways (of course, auto-dumping cart stops also make "quantum stockpiles" exploit trivial).
 * Things get really hilarious if there are duplicate creature entries after modding. You can end up with mysterious, typeless "meat", the extinction of the turtle, and even a fortress where instead of dwarves, you start out with extremely dwarfy elves.

Grand Theft Auto

 * Grand Theft Auto: San Andreas would occasionally spawn aircraft that had a flight plan going straight into the ground, assuming the player was at certain parts of the game world (the tops of a rural mountain). The dev team discovered this bug when the game was being tested and decided not to fix it.
 * This bug has been seen in the middle of a crowded intersection, which destroyed several cars and killed many people. Assuredly, worth the price of admission as the bug was not known of at that time.
 * There is another bug in this game where, in some 2-player situations, player 2 can decapitate player 1 (with the sword) and player 1 will respawn headless with blood spurting out of their neck.
 * A cool visual glitch can be triggered while riding the Mountain Bike. Mash the X button while holding the Square button and watch as CJ's limbs stretch, twist, and bend in all sorts of uncanny ways. Do it enough and he'll even start to melt into the ground.
 * While riding a bicycle, it's possible to climb up inclines at angles just shy of straight vertical by repeatedly mashing the accelerate button.
 * If you play the PlayStation 2 version of the game with a tool like HD Loader, the delay between spawning vehicles drops to almost nothing. This is mostly harmless, as the same amount of vehicles spawn, just sooner; however, it interacts badly with the buggy highway driver AI, which results in VERY BIG pileups if you approach certain intersections in Las Venturas on foot, or occasionally spontaneously on some highways with no provocation whatsoever. A well-placed grenade in this situation can set off a neverending chain of explosions that is continually fed by the rapidly-spawning vehicles adding to the pileup as cars are destroyed.
 * In Grand Theft Auto IV, there is a swingset in the game's version of Brooklyn that is unintentionally buried inside the concrete under it. The physics engine realizes this is a problem, and constantly attempts to dislodge the swingset with brief moments of infinite force. If you drive a car onto the swingset (or climb on it yourself), said infinite force will destroy the vehicle, kill the person... oh, and launch both of them into low Earth orbit. It's a popular spot for YouTube videos.
 * If you position your character on a ledge just right as the police are moving in to arrest him, a long line of police will jump onto the ledge and fall off like lemmings. Works when you hide next to billboards too. (See examples here and here.)
 * After hanging out with Roman, if you take him back to the Apartment but park so that the passenger door is blocked, he will cold-cock Niko in the jaw just to climb out of the car. In fact, any NPC will do that. It's especially amusing if it's your date who just thanked you for a wonderful evening.
 * Call up a friend to go drinking. Walk to the bar, or park just before getting there. Pull out a gun and go to the bar. Now you are stumbling around drunk with a loaded weapon that you can fire. Especially funny with a shotgun or automatic weapon. High probability of shooting yourself in the leg or accidentally blowing away your drinking buddy.
 * In GTA Vice City, sometimes if there is a body or object next to the open driver's side car door, and you try to get in, Tommy will instead run in a U from the hood to the back tire trying to find the door. Sometimes he will even bump into pedestrians who will then start fighting each other! A riot because the porr guy can't find his car door...
 * In Grand Theft Auto, pressing the horn button while on foot would make the player character fart and belch. This action can still be done if the player is killed.

Minecraft

 * Like Dwarf Fortress, the strange interactions of Minecraft's world create a lot these: Swimming up waterfalls? Teleportation via minecarts? Sand-on-torch floodgates? Glitch after glitch has been discovered, explored, and developed by the massive Minecraftian community, before being turned into yet another incredible, important and intriguing tool for future players. They've started fixing them now, much to the dismay of players who can now drown in a small waterfall.
 * No mob in the game can see you through glass, they all treat glass as a solid object - until they can 'see' you at least once, following which they will be able to detect you through any block.
 * A (now patched) glitch let you duplicate items by storing an item inside a chest, then closing the chest while still dragging the item, causing a dupe item to drop in front of you.Although the duped item would disappear if the player attempted to use or stack it, it could still be used to craft, making mass production of iron or diamonds a reality.
 * The booster cart glitch, which allowed minecarts to speed up considerably, had an entire subway system founded on it. Notch, one of the game developers, didn't get rid of them in a timely fashion, but added in a replacement feature (powered rails) that works without any glitches, albeit differently. He then proceeded to remove the glitch boosters in the next patch, along with boat elevators and rapid-ascent water ladders, to the dismay of the community.
 * In an attempt to make powered minecarts work again, the glitch (albeit weaker, but still useful) was reintroduced. Notch and Jeb just can't win.
 * If a multiplayer server is experiencing significant lag, you can see flying squids.
 * Normally sand and gravel blocks will be subject to gravity (the only two blocks in the game that are) and fall down if you remove the block supporting them. However, due to the way the game world is generated, you can end up with floating sand/gravel blocks. If you place a block next to one of these, the physics engine will recalculate the floating blocks which can result in large areas of apparently solid land suddenly caving in and collapsing. If done right, you can use this to make pitfall traps, or just make cool floating structures that shouldn't be possible.
 * In some of the older versions of the beta (prior to 0.8), using "404" as a world generation seed would create a gravel patch in this manner; upon destroying one of the gravel blocks, the sand and gravel in a rather large area would spontaneously collapse and reveal a giant sinkhole from sea level to near-bedrock. Various players had thus participated in the "404 Challenge", which involved surviving in the sinkhole with (among other limitations) no torches.
 * While not strictly a glitch, the water physics in Minecraft are very peculiar and players have found all sorts of inventive ways to exploit this to their advantage.

Other Games

 * True Crime was loved for the massive amounts of bugs that took place with its random crime missions. Notable examples are when the designated mugger tries to mug the player, a villain trying his best to run through the wall, a villain car being destroyed before the mission begins, or when a female was being raped by another female.
 * If you drive at full speed while heading directly at wall, the chances are you will drive through it as if it weren't there.
 * The space trading game Frontier: Elite II featured a 16-bit math overflow bug whereby the player could transit distances of exactly 655.36 light years instantly, using minimal fuel. The "wormhole bug", as it became known, was almost essential for exploring the outer reaches of the in-game galaxy, although sadly it was removed with later patches.
 * A more useful bug in Frontier: Elite II let you obtain as much money as you want. All you had to do was accept a mission to carry someone to a different system then try to sell your ship. You'd get the money for the sale of your ship, but the game wouldn't sell the ship because there was someone still on board.
 * The early versions of Frontier had another useful bug, there was a system in which gemstones had a negative value - they paid you to take them away - and in another nearby system they were illegal, which doubled their black market value. You could make ludicrous amounts of money exploiting this bug.
 * Elite II also had a bug which allowed laser turrets to be aimed while game time was paused. You could wait until the enemy was close enough, pause the time, take all the time you need to aim, fire your laser and unfreeze time to watch the enemy take a certain hit.
 * Crackdown has an interesting physics glitch made possible by the "Keys to the City" mode. Turn off pedestrian traffic, set your driving skill to four stars and spawn an Agency SUV. Drive as fast as you can on one of the larger highways with the Keys menu open, then when you reach any upwards slope, spawn a ramp truck. If done correctly, the SUV will be launched at an absurdly high speed sideways, usually either slamming into a building or flying a couple miles out into the ocean depending on where you were and how fast you were going. Seeing a tricked-out SUV doing barrel rolls as it flies sideways over a ferris wheel at Mach 2 can be quite entertaining.
 * Red Dead Redemption has quite a lot of these - including, most notably, the Demonic Horse (which seems to have epileptic fits that toss it a couple of metres in the air), The Gunslinger Dog (a NPC's model is replaced with that of a dog), The Bird People (humans flying around as birds), The Cougar Man and The Donkey-Lady (both of them animal-men similar to the above. The latter of which you can ride).
 * One of the few actually useful ones allows you to use Dead Eye - a brief moment of painting targets and shooting them with 100% gunshot accuracy - with molotov cocktails and dynamite. It functions exactly the same way, just with an invisible crosshair. Can you say homing explosive projectiles?
 * Horses have a stamina meter that's supposed to drain if a horse sprints at its maximum speed, but if you press the sprint button at a certain speed, the stamina will recover more quickly than it's spent without your horse losing speed, effectively giving it unlimited stamina.
 * Stagecoach rafting. Stagecoaches have a floating quality which allows you to sail along water. There aren't many places where you can successfully raft, but most of them can take you a long way before you stop. You can even get across to places you haven't unlocked yet. Sometimes, you can even see posses going for a sail in Multiplayer.
 * In Mercenaries 2, a glitch exists where if you lose enough times, particularly in the Bird Delivery Mission, for some reason the bad guys will stop shooting at the player. This glitch lasts until one quits the game. During this time, one can beat the side missions that are normally impossible to complete because of the attacks.
 * The first Mercenaries game also had a rather amusing glitch known to the community as "Spinning Artillery". If you shot a soldier driving the open-topped ZSU-57-2 and killed him, the vehicle would begin to spin in a slow circle until boarded or destroyed.
 * In the game Bone Town, one is able to have normal sex with the special characters in the Fantasy Mansion. Just need to stand far away from said woman, and slowly move in while hitting the Enter Key until the scene occurs.
 * In Dead Rising,  in Overtime Mode, Brock, is usually extremely difficult to fight and rather unfairly, the game takes away any weapons you had before starting the fight. However, there is a trick to get around this. One of the mixed drinks you can make, called Spitfire, allows you to turn your spit into a projectile of sorts for a few minutes. It's not that useful in any other circumstance, but if you make one before giving the last queen to , take it with you, drink it before entering the Jeep and defeat   as quickly as possible, you will still have the Spitfire effect as you start the fight with him. This allows you to run away a short distance, face Brock and spit at him repeatedly. He will block every attack, but he will slowly take damage and will eventually die. Call it unfair, but it's not like he plays fair either.
 * Saints Row: The Third has a glitch with special weapons like the minigun or shock hammer in Mayhem activities. Basically, you're restricted to certain specific weapons for the activity, and cannot pick up or select alternate ones. However, gang specialists and brutes, who have unique weapons, still arrive to attack you if you end up getting a ton of gang notoriety while causing mayhem. You can still hold the reload button to pick up their weapons once you kill them, at which point your character just holds them in their hand and acts as though the weapon doesn't exist, leading to such sights as holding a minigun one-handed or mashing it together with an RPG.