Everything Fades

"Pox: Crypto. What do you think happens to the corpses of all the humans of whom you suck out the brain stems? Crypto: I always figured they just faded away when I went around the corner."

- Destroy All Humans! Big Willy Unleashed

In video game land, dead things often have a habit of vanishing into thin air in various ways -- evaporate, disintegrate, blink in and out of existence, crumble to dust which disappears, etc. You can turn a room into a grisly scene of carnage, and return five minutes later to find it as pristine as when you first entered, even down to smashed or shot-up parts of the environment having repaired themselves; or if you stand there long enough, you can actually watch the corpses fade away.

There are three key reasons for this. The main one is that keeping track of all the dead people, dropped weapons and bullet holes throughout every part of the environment the player has been in requires an increasing amount of memory -- at least unless the game heavily restricts the player's ability to backtrack -- with little to no practical effect on gameplay. Another is that these objects could become actual obstacles that impede the player's progress -- in free-roaming games, you could potentially find yourself blocked off by insurmountable piles of corpses, overturned furniture, gutted vehicles, and so on. And finally, Moral Guardians may object to allowing players to do cruel and unusual things to a corpse for their personal entertainment.

Occasionally, the game meets you halfway by having the bodies disappear while leaving behind any useful weapons or items the character was carrying, so the player can double back and pick up the ammo they didn't have room for earlier.

Sometimes, this is accomplished by all enemies simply exploding when killed, so there isn't a corpse in the first place. This may have been more common in 2D platformers where any corpses at all would get in the way.

More common than it used to be since enemy characters in games are now almost exclusively complex 3D models with highly-textured surfaces and built-in Ragdoll Physics. Earlier games such as Marathon or Wolfenstein 3D, where the enemies were low-resolution 2D sprites, left everything the player killed on the screen for their own personal satisfaction.

Some games even have "corpse stay time" as a changeable setting in the options menu, for players with high-end computers. Others keep some corpses, like bosses, but fade the Respawning Enemies so they don't pile up. Yet another variant is where the corpses stay while you're there to see it but vanish when you move away.

Strangely, the dead body of the character relevant to plot is prone to not disappearing.

Compare and contrast with Disappears Into Light, when this happens to characters not because of space constraints, but due to plot reasons. See also Self-Disposing Villain.

See also No Body Left Behind for things that collapse into like dust or ash after death rather than a whole body fading a few moments after death/destruction.

Action-Adventure Games

 * Mostly averted in Shadow of the Colossus: The Colossi, upon defeat, would turn to stone and crash into the ground, and their corpses would remain there for the entire game. (You can actually go back to the stone corpses of the Colossi and activate a "Reminiscence Mode" where you can re-enact your fight with them, complete with old-grainy-film graphics.) However, any small creatures you kill (newts, birds) will fade into the ground.
 * In the modern remake of Ninja Gaiden, enemies will break apart into puddles of blood that will clean themselves, burn up or sink underground once offscreen, except for certain bosses. Mostly averted in Ninja Gaiden 2, where enemies or their Ludicrous Gibs will remain for some time after you're done with them.
 * In Legacy of Kain: Soul Reaver enemies don't disappear unless you remove their soul. Also the weapons remain wherever they landed provided you keep playing.
 * However, there is a problem with just leaving your enemies to just stay where they are. Not only do they come back to life, they can be enhanced with their OWN soul sucking abilities (when they hit you), but in the Spirit world, you will be attacked by the Wraiths that evolve from their untaken souls (and they come back after a bit unless the body is destroyed, which and only be done after killing the new powered up form, and eating the soul afterward). This can be particularly dangerous in high-level areas when enemies can pick you off easily despite your powers. FURTHER difficult if you slay them on something that does not allow you to get a second chance to kill them in the physical realm (the wall spikes, for example), and you have to suffer a wraith (or more) every time you pass by there in the Spirit realm.
 * The exploding-corpse version is used in more recent Zelda games. It varies, depending on the game, as well: In The Legend of Zelda the Wind Waker, the explosions are purple and spirally; in Twilight Princess, they are red, black, and more morbid-looking.
 * In The Legend of Zelda a Link To T He Past fallen enemies explode in a cloud of smoke resembling a skull. Skyward Sword echoes this.
 * Older 3D iterations of the series use this; notably Guays, ReDeads and Lizalfos. The rest of the time fallen enemies burst into flames (which are usually a strange color) and disappear.
 * The Legend of Zelda Majoras Mask featured an interesting Lampshade in the form of the Garo, a highly secretive order that taught their warriors to destroy themselves with a bomb when defeated, so as "to die without leaving a corpse".
 * In the original The Legend of Zelda game in the series, enemies would simply vanish when defeated (except for the Big Bad Ganon, who turned into a pile of ash). While this is naturally enough explained by the limitations of 8-bit graphics, the animated series based on the game would Hand Wave the phenomenon by having them not die so much as be teleported back to Ganon's lair, where they were kept in a really big jar.
 * Notably, in a couple of the games (Wind Waker being a good example), ReDeads stick around for a while after you kill them, much longer than other enemies, until finally fading/exploding.
 * Actually kind of a plot point in The Legend of Zelda Phantom Hourglass. The boss monsters dissolve into Sands of Time after being defeated, which is the fuel for the titular hourglass.
 * Irritatingly got worse as the Tomb Raider series went on (and the hardware it was running on improved); in TR1 and 2 enemies pretty much never disappear, 3 had them disappear after you had turned away for a little while, in 4 and every subsequent game corpses always disappear right in front of your eyes after a few seconds. In Legend and Anniversary this also extends to many physics objects. Eventually averted in Tomb Raider Underworld.
 * Monsters in Okami dissolve into patches of flowers when you kill them, since they're mostly demons comprised of negative emotions and Ammy is exorcising them. The bosses get fully-fledged Technicolor Deaths.
 * Cave Story has all enemies explode into clouds of smoke. A few, like the Gaudis, fall to the ground and shake a bit before they explode. The player character also explodes upon dying.

Action Games

 * In the Devil May Cry games, most enemies have an animation to cover their demise - for example, Sin Scissors shatter into pieces, Hells crumble into their composing sand, Abysses melt into the floor, and so on. Some enemies still just fade away, but they become less common as the games go on.
 * Same thing in The Creed. Any corpse will only stay on the ground long enough for a few rats to come out of manholes and water drains, devour it in a split second and then scurry off, giving the idea that they are extremely voracious critters.
 * Nemesis the Warlock for Commodore 64, ZX Spectrum and Amstrad CPC was a notable exception in the 80's. Corpses of regular enemies would stay on screen. Combined with each level consisting of single screen and amount of enemies per level this eventually resulted in huge piles of corpses, which became one of the trademarks of the game. Due to player's ability to walk on cadavers and due to the need to use the bodies to build "bridges" in certain levels this was also an important element in gameplay.

Adventure Games

 * While this trope is certainly older than Zork, probably going back to Space War!, Zork was the first to poke a bit of fun at it, with dead bodies, for no reason, vanishing in acrid puffs of smoke.
 * The bodies of the dwarfs in Colossal Cave did the same, but Zork's description of the process was longer and richer.
 * Lampshaded in Strong Bad's Cool Game For Attractive People episode 5, when the broken metal detector only fades after

Beat Em Ups

 * A classic example is Beat'Em Up Golden Axe, where defeated enemies would turn to stone on the ground - in the arcade version. The PC port has a lot less memory available, so has them disappear instead.
 * Lampshaded in the opening scene of Castle Crashers. When a wounded night stumbles into the feast hall, he collapses and simply blinks out of existence in the same manner most of the enemies do. Strangely, numerous other knight and enemy corpses can be found throughout the game, and only enemies your party kills will fade. In addition, a player character will only fade if there is no one left to revive him, and even then only outside of an arena.
 * Samurai Champloo: Sidetracked avoided an M rating by having opponents' images flattened and silhouetted in red, before being sliced in half. Then they just shatter and little gold coins spill all over the place. So, apparently their blood is made of money.
 * In Growl (old Taito beat-em-up; was ported to Genesis), dead enemies don't vanish immediately, but do if you stay on the same screen for a while. That's because for some reason the game treats them like dropped weapons, which disappear after a few seconds if not picked up.
 * In Double Dragon, defeated opponents blink out of existence. This also happens with Marian when she is killed at the beginning of the second arcade game.
 * Characters from the Scott Pilgrim Game explode into Canadian coins when they're defeated, as do many people in both the movie and the comic book it is based on.

Fighting Games

 * In fighting games with weapons, such as Pro Wrestling and the Super Smash Bros.. series, it isn't bodies that fade but weapons, usually after only 3 or 4 hits. This is largely for reasons of gameplay balance, and to make the actions on screen more interesting: while a real person wrestling on TV might hit someone three times with a chair and then toss it aside to keep things from getting tedious, someone playing on a console might be all to happy to eschew doing any moves in favor of hitting their opponent thirty times with the ring bell.
 * Notably averted in the Japanese game Fire Pro Wrestling Returns. Any weapons pulled out will stay where they drop throughout the whole match, and can be used ad infinitum. This is balanced out by a referee's five count leading up to a possible disqualification, though.
 * If playing Stamina Mode in Super Smash Bros.., your character will remain on the stage if you lose all your health. Other players can still knock you around, and even pick you up to block attacks.
 * What's especially freaky in Melee is that whenever someone's stamina reaches 0 they let out the same huge scream used when they're knocked into the background (usually a Big No), and time slows down as they do so.
 * In One Must Fall 2097, every hit knocks bolts and scraps of metal off of the robot, which dissolve shortly after hitting the ground. However, there's a cheat code that makes them reappear at the top of the screen and continuously rain down until the match is over.

First-Person Shooter

 * In Turok 2, not only the corpses fade, so do the children and prisoners you rescue from their locked cages. They say thank you and fade while still doing their idle animations.
 * In Doom 3, the hell creatures fizzle away to nothing when killed; the zombified humans, logically enough, do not unless you hit them.
 * Corpses also disappear in the GBA versions of the first two games.
 * Varies in Half Life and its sequels. For example in the first game, most enemies placed in the map directly would leave corpses unless blown up by explosives, but ones made by a Mook Maker would fade. In Half Life 2 there were fifty-foot enemies called Striders, whose bodies stayed behind if you had a sufficiently powerful machine, but otherwise just disappear in a small cloud of sparkles at their Critical Existence Failure...
 * No One Lives Forever, a '60s spy movie pastiche with a female lead, issues a special body-dissolving powder with the gear, requiring the player to actually get close to a victim's body to dispose of it. According to in-game exposition, Cate Archer's slight frame was considered inadequate for stuffing bodies in lockers. In the sequel she was suddenly strong enough to carry bodies around, though slowly. Ironically, though, bad guys in the sequel carried the body-dissolving powder themselves and would use it before searching for the culprit.
 * However, the options menu (at least in NOLF 1) lets you enable instant fade-away, so rather than having to use the corpse-remover, it just makes them fade away.
 * In the Area 51 First-Person Shooter, this is handwaved as being an effect of the alien biotech used to create the monsters and clone soldiers you fight, and the first time it happens, a character does act like corpses vanishing is bizarre.
 * A bit irritating in the Alien vs. Predator series. The predator can collect the skulls from enemy corpses for points. He does this by using his melee weapons, so close proximity is required. The corpses vanish really quickly though, so a Predator player wishing to amass a lot of points necessarily has to come out of cover and get to where the corpse is, giving plenty of opportunities for enemies to shoot him full of lead. A Predator player will also wish to use the less powerful weapons, as a careless shot from the plasma weapons can vaporize a target's head, making it impossible to collect the skull.
 * Played with in dreadful FPS Haze. The soldiers/mercenaries from the Mantel corporation are under the influence of a super-drug called "Nectar". While on this chemical bodies appear to fade away and there is no blood or gore. Unfortunately, when off the chemical the engine is so poor that bodies still disappear after a while, this time for no reason at all, and the gore system is so anaemic it doesn't even product impact marks on bodies, something GoldenEye managed.
 * In Bioshock the corpses of Splicers and Big Daddies as well as the wreckage of Security Cameras and Gun Turrets remain either indefinitely or until a certain amount of corpses are on the ground, at which point some of them de-spawn and are replaced with "Lockboxes" containing whatever the corpse was carrying before. It's assumed that empty lockboxes will despawn after a while or after the same limit is reached. However because there's not much to buy and items that are only used 3-4 times in the game continue to drop after all the opportunities to use them have passed...
 * The Metroid Prime series has a few variations. Smaller enemies will typically explode when defeated, with the bits evaporating. Larger enemies will go through a ragdoll animation, then disappear. But anything killed by a Metroid will become a fragile husk, which turns to dust at the slightest provocation; this last one is used to creepy effect in Metroid Prime 3, when you find a derelict starship filled with such bodies.
 * Also, there's the burning animation. When you kill an enemy with the game's fire-based beam (Plasma Beam for Prime, Light Beam for Prime 2, and Plasma Beam or Nova Beam for Prime 3), they will completely burn up into black dust.
 * In the rest of the Metroid series, enemies explode to nothingness when killed. Some lingering corpses can be seen in some of the games, including Metroid Prime games, but they usually died offscreen.
 * The only exception being Metroid Fusion. Since all the enemies are actually shapeshifting parasites, they dissolve and turn into floating protoplasm when you "kill" them. If you don't absorb them, they'll eventually fly somewhere else in the room and turn back into monsters.
 * The Jedi Knight game series dealt with it in different ways. Jedi Knight and Mysteries of the Sith had bodies that wouldn't vanish for some time. Based on the Id Tech 3 engine, Jedi Outcast and Jedi Academy had bodies that would vanish almost the instant you turned your back (mechanical enemies just exploded). It was kind of disappointing, when Jedi Knight's predecessor, Dark Forces, being sprite-based, was able to let the stormtrooper bodies pile up like cordwood.
 * Outcast and Academy actually have three different ways of removing corpses in multiplayer. If one is hit with enough weapons fire, they'll disintegrate like they were shot with a fully-charged disruptor. If they're let alone long enough, they'll be engulfed in either white light or red lightning, depending on their Force orientation.
 * Justified in Quake IV; when a Strogg is killed, the Nexus (the Strogg's sentient techno-organic communication system) teleports the dead body to a facility to be broken down for future usage.
 * This was averted in Quake II, which IV directly follows. Corpses stay where they are. Apparently, in between one One-Man Army going and completely wrecking their homeworld, and the next One-Man Army showing up, they finally got those teleporters working.
 * Since it's based on the same technology as Doom 3, it's save to assume that the change in the Canon Discontinuity was not caused by some new technology but by a more convenient development.
 * The many, many corpses created by the PCs in Left 4 Dead fade at different rates, depending on how many enemies are currently around; sometimes they'll stick around indefinitely, other times they'll fade before they even finish their death animations. It's a testament to the atmosphere and intensity of the game that many players don't even notice when the corpses disappear.
 * Played painfully straight in the gimped Australian version of Left 4 Dead 2, where all enemies fade quickly and conspicuously out of existence, sometimes even before they hit the ground.
 * Just as painfully obvious in the German version, especially when a survivor is killed, and the others will then go "Oh no! Not Francis!" while staring at a piece of ground with nothing on it except maybe a puddle of blood.
 * In Team Fortress 2 corpses will remain until you respawn and die again. Your Eternal Reward, a special alternate Knife for the spy, plays with this. Upon a successful backstab, it cloaks the corpse, muffles the death scream, and changes you into the person you just killed, all within the span of a second. While it sounds like it should be easy to spot, it's actually very hard, especially since you'd be paying more attention to the other 10 or so people shooting at you than where that sneaky engineer or pyro disappeared to.
 * Painkiller enemies 'pop' out existence leaving their souls to be collected.
 * Mostly averted in the S.T.A.L.K.E.R. series. bodies will stay around for in-game days to weeks, and guns will stay as well, however: if you leave the area and come back, strangely they will stick up, rather than lying on the ground.
 * Perfect Dark does this oddly. Corpses will generally only fade if you stop looking at them for a few seconds, but if you kill enough guards in the same area, you can watch them fade away.
 * Borderlands plays this trope both ways. Almost every enemy or boss in the game will appear to disintegrate after a very short amount of time, except the Rakk Hive. Upon defeating it, the body will remain until you leave the level. The body can even be climbed on, making it also the only solid corpse in the game.
 * Enemies killed in The Conduit fade out with a nifty evaporation effect.
 * Appears in GoldenEye which makes sense given the sheer number of enemies in some levels.
 * Like the Quake example above bodies in Prey vanishing is probably them being 'reclaimed' by the sphere.

Hack and Slash

 * In the Dynasty Warriors and Samurai Warriors games, enemies fade away as soon as they hit the ground. Which is just as well since you kill them by the hundreds if not thousands.

MMORPGs

 * The various criminals and monsters that can be "killed" in City of Heroes fade away in front of your eyes if you hang around long enough, but this may be a secondary usage of the city-wide teleporter system that automatically hospitalizes fallen heroes -- similarly automatic incarceration.
 * Cryptic's Star Trek Online is much the same on the ground; bodies disappear after a short time of lying around. In space play, however, large ships explode and some, like Borg cubes, will leave wreckage over the map, careening off at a reasonably related velocity. They also manage to avert another common aspect of the "mechanical enemies disappear by exploding" by making the explosions from disappearing ships actually dangerous - the explosion from the aforementioned Cube can easily destroy the player along with it if they're too close.
 * World of Warcraft has a set Corpse Stay Time in their respawning cycle. Corpses do last for a few minutes after they're killed, but fade when they're respawned; if you want to loot them, you have to do it before they fade.
 * If you don't loot them, corpses can stay for quite a long time; raid bosses with items on them linger for up to an hour. Empty corpses always vanish within several minutes at the most.
 * They vanish pretty much instantly after being skinned for leather, though (or in some cases in the expansion, after they've been mined or harvested).
 * There are two exceptions: Player corpses can stay for a very long time if the player doesn't release his spirit (there is a 6 minute timer in the main world, but logging out bypasses that until you log in again), and some places have corpses that are there for "decoration" or quest purposes. In one dungeon, some corpses also act as traps, releasing several maggot-like monsters when someone gets close. In that case though, the corpse fades afterwards.
 * Players have taken advantage of the 'Log out/timer stop' element to create what has (artfully) been called 'corpse graffiti'. Essentially, the player creates several 'throwaway' characters and sets their each of their names to one word of a pre-determined message, then logs them in individually and suicides to create and display the names in the proper order.
 * Gold sellers have also taken advantage of this to bypass measures taken to prevent them advertising their services ingame. Except they don't use character names for their graffiti, but spell out their site's URL with the corpses themselves.
 * Perfect World does this differently with different mobs. They always fade away (except for the things you would find useful), but they have different animations and noises before they do so. Mantises sigh and make a clanking sound as they collapse, pterosaurs fall down on their side while somehow still defying gravity to the point that things they DROP stay in the air, Tuskmoors do a little dance thing and just fall, Taurocs look like they are going to hit you with their club one last time, and torches... ugh... They scream "CURSE YOU!" in their last breath... to make matters worse, it does this evil laugh the whole time you're fighting it. If you're a ranged class and it's closing in on you, laughing in relish the whole time...
 * In zOMG!, as in most RPGs, all enemies fade away after death. Some have a justifying animation (Gramsters for instance, collapse into dust, while Predi-Pups attempt to blow themselves up), while others simply collapse and vanish. This is somewhat justified by most of the enemies being composed of G'hi. Strangely, even the endgame enemies (a majority of which are not G'hi based) fade. Though in the case of the, it's possible they simply went to respawn, as their death animation is similar to the "Dazed" animation for most player characters. It still doesn't explain how . But then again, you get teleported to the Developer's Room immediately after killing it, so you don't actually get to see what happens to it's remains.

Platformers

 * Handled oddly in the old Commander Keen games for DOS machines. In the original trilogy, enemies leaped up into the air with expressions of shock/pain when shot with a ray gun. The roasted corpses (they appeared to be surrounded by some sort of flame or energy while in their death throes, which would suggest a roasty-toasty manner of death) stayed in the room for a time and then faded away. The later games in the series, trying to be more kid-friendly, replaced the ray gun with a stun gun. The "neuralizer ray" had the same effect as the plain old Death Ray, but dispatched enemies had cartoony stars circling their heads. Despite this supposedly gentler method of dealing with enemies, the bodies never went away and kept the bizarre "oh no, I've been shot!" face while stunned. (And if you read the story section of the help, you'll learn that Keen shot his parents with the gun before the adventure began. As the extro states, "hopefully this won't affect his allowance".)
 * It doesn't seem to be permanent for the monsters either - some, such as Arachnuts, recover and come after you again.
 * Partially averted in Banjo-Kazooie, enemies do not respawn and the health they drop remains remains forever until you die or leave the level. The later Banjo games fixed this.
 * In Donkey Kong 64, enemies will fade away after being defeated - except for bosses, of course. They get defeated spectacularly.
 * Ratchet and Clank FINALLY got around to justifying this by Deadlocked: the Nanotech that otherwise keeps people alive will destroy their host bodies upon death and seek out a new host, both explaining the disappearing corpses and Ratchet's general XP. Doesn't quite explain why Ratchet never poofs out of existence though... besides the obvious.
 * When a character dies in the Spyro the Dragon series they would burst into sparks and vanish.
 * In the first Spyro, explained right in the manual. Gnasty Gnorc's spell turnes the dragon treasure into the monsters; "killing" them is really just dispels the enchantment. Why creatures in the other worlds work like this, well...
 * In the mental worlds in Psychonauts this makes sense, since nothing there is actually real. The telekinetic bears and pyrokinetic cougars, on the other hand, do the exact same thing for no particular reason.
 * The Crash Bandicoot games (at least, the main PS 1 ones) just showed enemies flying into the distance after being slapped by the titular character. Unless you jumped on them, in which case they disappeared in a cloud of smoke, occasionally being flattened first.

Real-Time Strategy

 * In Age of Mythology, only heroes' bodies do not fade-because heroes can be resurrected if your civilization is doing well.
 * The RTS game Warhammer 40K: Dawn of War leaves a percentage of the bodies killed on the screen indefinitely. This percentage can be modified from the in-game settings; depending on how powerful your PC is, you can go from all bodies fading to the entire battleground being littered with corpses by the end of the level. The Expansion Pack Dark Crusade introduces the Necrons, who have the ability to animate these corpses long after they're created. The Tau Empire also has Kroot units, which can feed on the corpses of organic enemies to gain an immense boost in health and damage.
 * The Warcraft series turned this into a gameplay mechanic. As long as the corpse stays, it can be used for several spells. In Warcraft III, the undead Scourge, which have the majority of them, even have meatwagons (their siege unit) that can carry corpses to prevent decay (their animation implies they use spares as ammunition). One of their buildings also generates corpses for the same purpose.
 * The other Blizzard RTS game, Starcraft, has the same mechanic of disappearing corpses, almost instantly after a short death animation.
 * Infantry units in Star Wars: Empire at War will eventually fade away after dying, though there is a mod that prevents that (same one with the "no unit cap"). Most vehicles on land and fighters in space with instantly explode upon dying, but larger ones will remain for awhile (space units will break apart, float "down", then explode. Capital ships last longer in that regard) then explode, though even then (specifically with the AT-AT) they may still instant-explode. Oh, and sometimes fighters will go spinning out of control first before exploding.
 * Averted to the extreme in Bungie's Myth games: bloodstains, fire, and explosions permanently mar the ground, and every severed limb, every piece of destroyed scenery, and even fragments of broken arrows remain until the level ends. This is tactically relevant, especially in multiplayer, as you can see where battles have occurred before you got there.
 * It's even more relevant in that ghols can pick up the blades that have been dropped and use them as thrown weapons. An explosion can also turn the dropped and shattered sword or ax blades into improvised shrapnel.
 * Averted in Supreme Commander, where destroyed enemy units and buildings will usually leave their charred remains behind. This isn't just realistic: You can actually harvest them for mass (the game's less abundant resource).
 * Supcom inherits this from its predecessor Total Annihilation, which even had multiplayer maps themed around a devastated urban area. These had no normal metal deposits, so the player was expected to reclaim the destroyed buildings, cars, powerpoles etc.
 * Also worth noting is in both games, things destroyed by a powerful blast (such as a nuke) are obliterated and leave no reclaimable wreckage.
 * Dead allies and enemies in Populous the Beginning turn into blurred ascending souls a short while after death; sometimes they appear like a transparent version of themselves instead.
 * Both used and averted in Company of Heroes: dead infantry fade quickly but most vehicles leave a wreckage indefinately which can be used as cover, scavenged or destroyed.
 * In RHDE, a unit that takes three hits "faints" and disappears.

Roguelike

 * Nethack's take on this: after you kill a critter, assuming it was made of meat, it may or may not leave a corpse. If it does generate a corpse, said corpse lingers for a while before rotting completely away and disappearing. Some corpses are automatically poisonous to eat, most of the rest become poisonous if you wait too long to chow down. Any gear the critter was carrying gets left behind; if you don't clean up after yourself, Nethack dungeons tend to get a bit cluttered.
 * Being based on a game that didn't use this trope much, Doom the Roguelike also tends to leave a lot of slain enemies laying around, while allowing explosive damage to destroy the bodies. In dealing with Archviles or Nightmare difficulty, destroying the bodies quickly is a good idea.

Role-Playing Games

 * In Monster Hunter, the corpses of slain foes would vanish within set times. These times were wildly different as enemy wyverns and dragons will take minutes to fade while pesky raptors would vanish in mere seconds. This could become aggravating for the player because taking the time to carve dead monsters would result in acquiring new items so fighting a group of raptors often resulted in a player missing half of his or her potential carves.
 * Deus Ex is also noticeable for lacking this effect, even having flies gather over the dead eventually as in Diablo above; if the bodies ever did vanish, there was always an explanation given in-game. However, NPCs friendly to the player would fail to react at all to the sight of a dead or unconscious ally.
 * This verisimilitude comes at a terrible price: Individual save files often exceed 10 megabytes!
 * The reacting to bodies was originally in the game, but it caused too many problems with AI, and was Dummied Out at the last minute. There's a lot of it left in that can be seen and enabled with the SDK.
 * Unless the player is carrying the corpse on their shoulders, in which case some friendly and civilian NPCs will flee in terror as if the player had just fired a shot into the air.
 * This goes double for Gary Savage, who will alternate between fleeing in terror and running back towards the player to speak with him (under specific circumstances).
 * This trope was turned into a hazard in the sequel, Deus Ex Invisible War, where Illuminati Commandoes would dissolve, but turn into clouds of toxic gas.
 * Also hazardous for the many enemies Made of Explodium.
 * In Deus Ex Human Revolution, Nothing fades, ever. This includes bodies, weapons, Inventory items, Etc.
 * This leads to many players using Adam's apartment as a supply dump.
 * This was so explicit in The Elder Scrolls: IV Oblivion that when you started a quest, it spawned a body you had to search. If you waited too long, the body disappeared and you couldn't complete the quest. Bodies do, however, tend to linger for a surprising duration, remaining in cases hours, even days, of game time later. Corpses don't vanish when the character is present, however, lending a certain veneer of plausibility to the idea that they were, perhaps, removed by others.
 * With Oblivion the default time frame for a corpse to disappear is 72 hours without the player present (IE: you have to be out of the area with the corpse for 72 hours in a row, coming back resets the timer.) That's in game time, so it's only about an hour or two of consecutive play. Blood on the other hand fades after 30 seconds or so, and arrows shortly after that.
 * Similarly, in The Elder Scrolls III: Morrowind, you can "dispose" of an enemy or monster corpse, or leave it lying around. Corpses are disposed of automatically after a set amount of time.
 * In Final Fantasy I, slain enemies just disappeared in the blink of an eye. From Final Fantasy IV onward, the enemies faded in a purple haze, although they went through death throes first in Final Fantasy VIII. Final Fantasy X and X-2 were exceptions; it was explained that the monsters were restless souls that gathered together "pyreflies" (supernatural fireflies) and manifested as "fiends" - thus, killing one caused it to break apart into the component pyreflies, which flew away. (Mechanical enemies, meanwhile, just blew up or fell apart, but humanoid enemies still simply vanish without explanation.) Final Fantasy VII and its Compilation show bodies dissolving into The Lifestream, even in The Movie. To what extent this happens to humans and other 'normal' animals is not really explained.
 * Final Fantasy has used the fading death trope as a signifier of Final Death as, for humans this is always depicted as the character blinking out of existence (see Scott or Galuf.)
 * Similar to Warhammer Fantasy Battle, RPG Diablo II leaves bodies populating the floor until the character leaves the area in order for certain spells and abilities to be useable (raising the dead, searching corpses and, particularly effective, making bodies explode to the detriment of those nearby). There are searchable bodies of never-seen alive NPCs which stay there forever.
 * In the Fallout games, bodies remain for as long as the player is onscreen and continue to lie about for several game-days. After a while, though, the bodies vanish and are replaced with pools of blood, giving the impression that they've been eaten by wildlife. The equipment that the bodies were carrying remains, however.
 * In Fallout 3 you are able to pick up and move the bodies (or their extremities) around, which can lead to the corpses of entire gangs occupying a single bathroom stall providing you're so inclined.
 * However, like Oblivion, after 72 game hours in a different cell, enemies can reset and disappear or respawn, depending on who or what they are.
 * Justified in Vagrant Story; the city of Lea Monde is filled with a mystical force called the Dark which causes those who die within the city to disappear in a puff of glowing purple dust. As a nice bit of attention to detail, the bodies of enemies killed outside of Lea Monde during the opening sequence do not vanish.
 * Notably averted in the Baldur's Gate: Dark Alliance series, where you could revisit most locations that you had been to to find that the hordes of corpses and rubble were still there. This might explain why the games' save files took up so very, very much space...
 * The Baldur's Gate RPG series--and games based on the Infinity Engine in general--meanwhile, had dead bodies that eventually faded (assuming they weren't exploded into giblets from massive damage). Also, Baldur's Gate had a special feature in some areas that respawned enemies some time after their corpses disappeared out of the Player's Point of View.
 * In Final Fantasy V and Final Fantasy III someone who was a PC dies in a cutscene, and their body fades out. Especially fun in V when the party tries to cast Revive and use Phoenix Down, but to no avail.
 * Similarly, in Tales of Phantasia when.
 * Noise in The World Ends With You dissolve into their soul-code upon being erased and are broken down into soul-fragments subsequently. The player as well, by the way, you can even "see" Neku's and his partner's fate a split second before the Game Over-screen. Apparently, for a scattered soul everything looks like a broken TV.
 * One of Neku's exclamations before dying is, in fact, "Huh... I'm fading?"
 * Not just Players fade, but Reapers too. That probably has something to do with the fact that everyone is.
 * An In-universe example:.
 * Sadly leads to Narm in Wild ARMs Alter Code F and Wild ARMs 5--dead characters sometimes fade out among rings of light in highly detailed FMV cutscenes.
 * Some Mario enemies, especially in the RPGs, do this after a whole bunch of colored stars fly out of them at zero health. On the other hand, it's not particularly consistent, since about a third dissolve into light and then fade, another few explode, some turn into clouds of smoke, Bowser gets his skin melted off in one game and bosses in Super Mario Sunshine melt into paint.
 * Justified in Sunshine as the enemies are made of paint. In the Paper Mario series the stars represent Experience Points; if an enemy gives no experience they just flatten and disappear. In the older PlatformGames enemies would just vanish or fall off the bottom of the screen.
 * Neverwinter Nights enemies quickly fade leaving their items in a small bag.
 * When creating a map in the NWN editor, one can set the corpses to stay on screen. Some of the corpsess in the campaign itself stick around as well.
 * Somewhat justified in Kingdom Hearts with the Heartless, Nobodies, and Unversed, given that Heartless have no bodies (with the darkness drifting away, and the heart returning to Kingdom Hearts), Nobodies are said to dissolve back into darkness, and Unversed are made up purely of negative emotions.
 * Justified, but never fully explained, in Hybrid Heaven, where any killed Hybrid, alien, or clones would de-materialize (shown by light leaving their body), and then explode, not leaving any traces. Even lampshaded in the intro, where when a Hybrid is killed and de-materializes in front of another person, one of the Hybrid agents says not to worry about it because the evidence is gone. However, this de-materialization only applies to the Hybrids and their non-AI allies, as the other enemies (scanners and robots) would simply explode upon defeat, and the non-Hybrid alien Gargatuans would not de-materialize upon death. However, it is never fully explained exactly what causes the Hybrids and only the Hybrids to de-materialize.
 * Justified by the unstable nature of the monster's bodies in Parasite Eve 2. Near the end of the game, the monsters are replaced by Golem Cyborgs, whose bodies do not vanish when killed, and are even still present when you return to an area, a rarity for a Playstation 1 game.
 * Late in the game when a monster you've just killed doesn't fade you know what's coming...
 * In Dark Souls, player characters fade away when they die and leave a bloodstain containing their souls and humanity. They also respawn at the last bonfire they used. Most of the enemies that aren't run of the mill Hollows also fade away when they die.

Simulation Games

 * Averted in Animal Crossing: No matter how long you leave that item there, it won't fade. Ever. Even after a real-time year, it'll still be hanging around--even, oddly, if it's a food item like fruit or candy. A lot of the game's saved data consists of repeated "nothing is in this grid cell" markers in order to avoid having to Cap the items per acre. Items do occasionally disappear to make way for a new building, in which case a neighbor turns the item in to the Lost and Found. However, trees you cut down do fade, even if their stumps stay--your neighbors will lampshade this and wonder how the tree trunks do that.
 * In Sim Ant, ant corpses eventually disappear. If the spider gets killed, the body will stick around for a while before eventually turning into a few pieces of food.
 * In the Creatures series, dead Norn and Ettin corpses will lay on the ground for a minute or two before disappearing in a cloud of smoke and lights while bells ring. For a Grendel, they decompose into a puddle of bubbling goo.
 * Enemy ships sink in the Naval Ops games and the water is always deep enough that you never run aground on wrecks. In Warship Gunner 2, you can watch them drifting down when you command a submarine.

Stealth-Based Games

 * Absent from many sneakers, including Splinter Cell and Thief requiring the player to carry and hide bodies to avoid alerting other guards.
 * In Metal Gear Solid, dead enemies disappear, but unconscious enemies must be hidden from their comrades in lockers, creating one of the game's most emblematic internal tropes, second only to the cardboard box. In the remake and the sequels, dead guards stick around.
 * Unless another guard discovers the corpse, that is. If that happens, the guard will check for lifesigns, then the dead body will blink out of existence as he radios in that something's up.
 * Lampshaded and/or Handwaved by the defeated Vulcan Raven: "However, my body will not remain in this place. My spirit and my flesh will become one with the ravens. In that way, I will be returned to the Mother Earth who bore me." When Snake looks back, his body is gone, only his gatling gun is left behind.
 * That's because the ravens ate him.
 * In Metal Gear Solid 4, the corpse of a normal PMC soldier sticks around. However, if you kill one of the elite FROG soldiers, their bodies magically fizzle away in blue flames, without any clear explanation why.
 * According to the Metal Gear Solid Database, the FROG soldiers have nanomachines that enhance their abilities even more than normal nanomachines. To prevent these apparently-advanced nanomachines from being captured by "the enemy", when a FROG soldier dies, the nanomachines instantly overheat and burn the body from the inside out. Squick.
 * In Assassin's Creed: the corpses of slain guards do linger around, and can be used to distract other guards or cause pandemonium among civilians. However, if you leave the Animus and re-enter, the guards are still dead but their bodies have disappeared.
 * Averted in the Hitman series: bodies stay around for the entire hit. In Hitman: Blood Money, when they are discovered by security, the security member will bag the body and drag it to the security office, where 47 can find the macabre scene if he's been on a rampage.

Survival Horror

 * In Resident Evil 4 and 5, the enemies collapse into piles of goo when they die. This goo itself evaporates in short order (or dissolves if in water) - this, however, is only true for the basic 'Ganados' or 'Manjini' enemies. Certain, more rare, types of enemies often leave lasting corpses, that remain indefinitely (usually because they might be carrying a key item).
 * Other games in the series feature bodies that disappear once you leave and then re-enter an area. This was lampshaded in the first film adaptation, where the characters return to the "laser corridor" to find that the bodies of their dead teammates have mysteriously vanished.
 * The Gamecube-exclusive remake of the original Resident Evil subverted this trope (but only with basic zombies). Any zombie that, er, "dies" by any method other than burning, exploding, or decapitating will stick around even if you leave and re-enter. These zombie bodies must be incinerated posthaste or they will come back later as the much more dangerous "Crimson Head" zombies.
 * A similar fate befalls slain enemies in The House of the Dead 2, but not the bosses. In the first game of the series, they just faded away in conventional fashion.
 * In House of the Dead 2's Arcade mode, lesser enemies melt into a puddle of icky green soup.
 * In the first two Alone in The Dark games (and perhaps part three), monsters' corpses disappear into a cloud of colorful bubbles (or smoke) soon after killing.

Third-Person Shooter

 * Mafia: The City of Lost Heaven was amazingly good about this, where you could shoot a car and have the driver flee in panic, go all the way across town, stay there for an hour, and then chance upon that same car, with the same bullet hole in the chassis. No long load times either. One of the many amazing things about the game that the sadly relatively unknown game has that puts it a leg above the other such games at the time . The Playstation port, however, is an entirely different story. It's... well... horrible.
 * That said, dead things (cars, people) eventually disappear, though you have to be a ways away in order for it to count. Broken objects (fire hydrants, streetlights, phone booths) aren't fixed unless you're doing story mode.
 * Justified in Giants: Citizen Kabuto by having the paradise terrain infested with ravenous scavenger critters just under the surface. Upon a creature's demise, they would pop up, rapidly devour the newly dead thing and then worm back into the soil.

Turn-Based Strategy

 * Mostly averted in Jagged Alliance 2. Soldiers killed outside will still be there later. After half a day or so, the body is visibly rotten, and crows peck at the corpse. Your mercs will make comments when seeing these corpses. (Everything from 'Oh my god, that is so revolting!' to 'Will you look at that! Hey, when do we eat?') As well, the crows fly away if you get close, or you can shoot at them for target practice (or if your merc is really good at sneaking, sneak up to them and punch them). After a few days, the corpse disappears, presumably rotting away to nothing. No sign of the skeletons, though. As well, soldiers killed inside a building just disappear rather than rotting.
 * Averted in Final Fantasy Tactics Advance, where corpses stay on the battlefield for resurrection purposes. On the downside, the judge has to move corpses around from time to time to avoid them being abused as obstacles. The sequel however plays this straight, and resurrected teammates just come back to whatever square you use the appropriate item or spell on.
 * All defeated units, be they enemies or allies, vanish in a swirl of light in Jeanne D'Arc. Don't worry, they can be revived --with a high-level, high-cost spell that shows up near the end of the game, and which restores the ally by the side of the caster instead of his or her original location.
 * Most units vanish instantly upon death in Nippon Ichi's strategy RPGs. The only exception to date is Phantom Brave, where piles of corpses can become impediments to movement and targeting. Or a source of improvised weapons. This also leads to the annoying gameplay mechanic (exclusive to Phantom Brave among Nippon Ichi games) where corpses can be destroyed through additional punishment-if this happens to one of your phantoms, they become Deader Than Dead (triple-dead, since they were dead to begin with?) and reviving them becomes slightly more difficult.
 * Shining Force II has a dramatic, serious death of a king or something. You know that it's a serious death because he blinks slowly, then quickly, then disappears (as opposed to blinking away quickly or spinning in circles).
 * Super Robot Wars enemies usually explode upon death since most are Humongous Mecha or other vehicles.
 * Every dead unit in every Fire Emblem game ever fades away after being killed. In most games, assuming one has battle animations enabled, they'll even fade twice - once on the battle screen, then again immediately thereafter when you return to the map screen. The same even carries over to most cutscenes, and instances where the body of a deceased person remains to be interacted with are quite rare. The characters still talk as though the deceased individual(s)' bodies are there, though.

Wide Open Sandbox

 * In the Grand Theft Auto games, bodies go through two stages of disappearance. First they're there; then they're gone but there's a chalk outline where they had been; then the chalk outline vanishes. The burnt-out hulls of destroyed cars also disappear after a short time. However, simply abandoning a car on a sidewalk may result in the player finding it there later. Emphasis on may; any player that relies on this to any great extent will find himself boned sooner or later.
 * Supposedly leaving the door to the car open (not in a closed state) will allow the car to remain more frequently. Which, seeing as how there are NPC carjackers in the game and regular NPC will sometimes drive unoccupied cars, this doesn't make single lick of sense if trying to apply a smidge of logic.
 * Disturbing in Bully. Defeated enemies fade away, as in all the other examples given here. Problem is, none of them are actually dead; in fact, one can merrily keep kicking downed victims and watch them respond, holding whatever you strike. Then, after a few minutes ... they evaporate. Considering they never actually die though, it's probably assumed they eventually just got up and walked away.
 * Played with and lampshaded in the Destroy All Humans! series. In "Big Willy Unleashed" its revealed that when Crypto kills people the reason the bodies disappear is because Pox gathers them up to be ground up into meat for his fast food franchise. When Pox asks Crypto what he thought happened to the bodies he just says "I always assumed they just faded away somehow when I went around the corner", which Pox considers rather ridiculous.
 * In The Godfather game, your victims will eventually disappear after a while, along with the blood pool, while items seem to take longer.