Collision Damage

""The Goomba shuffles sideways toward you and barely touches you with his body. For some reason, that makes you almost die.""

- Kingdom of Loathing

Perhaps the character bruises easily. Perhaps the enemy is toxic. Perhaps they weren't able to give the enemies an attack animation. Or perhaps the character is just obsessive-compulsive.

Either way, touching an enemy damages - if not outright kills - the player. If you're lucky, you might survive, although you may lose a Power-Up or two. On the plus side, Mercy Invincibility usually kicks in at this point. This is part of the reason why it seems like everything's trying to kill you.

Often the Invincibility Power-Up will give you Collision Damage effects on the enemy. This may even affect minor boss enemies.

This is a very, very old trope, dating back to the original Donkey Kong and even to Space Panic at least. It is most commonly seen in the Platformer; it is never seen in the Fighting Game or the RPG. It's also a Discredited Trope, as many modern platformers have discarded it.

This tends to be a bit easier to believe if it's a vehicle-based shoot 'em up. Flying one of the choppers of Twin Cobra into an enemy chopper is usually about as helpful there as it would be if you took an AH-64 and used it to kiss a Hind. (Hint: not very.) It's just more blatant when it's a human(ish) victim and the enemy really just wanders by it.

It's particularly jarring when the boss attempting to swing its claw at you does the same amount of damage as you accidentally touching the claw. Apparently, attacking doesn't hurt more, just makes you more likely to touch the Big Bad.

This will often happen even if facing an evil twin or otherwise "normal" opponent.

Not to be confused with the real-time model damaging employed in modern 3D games. See also One-Hit-Point Wonder.

Action Adventure Games

 * In the 2D The Legend of Zelda games, most enemies had the Touch of Death. In the 3D games, most enemies didn't.
 * Touching any of the Heaven Smiles in Killer 7 can prove fatal to characters low on health. This is a Justified Trope, however, because they all explode on contact.
 * La-Mulana has plenty of it. However, it doesn't actually impact your Life Meter very much, so it would take a very long time for a bat to kill a player. It's hardly a minor annoyance, though, since it can easily push you into a pit, and if you're standing on a ladder you will get knocked all the way down.
 * Unsurprisingly, colliding with most of the bosses is much more damaging than touching a mook.
 * Contact with enemies in Iji deals armor damage over time. However, thanks to Mercy Invincibility and a large health meter, it's still possible to simply run through some levels without dying.
 * Which you will have to do sometimes if you want to get the alternate "Pacifist" ending.

Action Games

 * Silver Surfer was Nintendo Hard because just touching a wall would result in the character's death. Often the lethal parts were indistinguishable from the background. Especially odd, because the Surfer is one of the most powerful and nearly invincible characters in the Marvel Universe.
 * All of the Contra series. Worse, you are almost always a One-Hit-Point Wonder, meaning that practically anything even remotely malignant is fatal. I mean, c'mon, you are a super muscloid juggernaut commando with muscles all the steroids in Major League Baseball couldn't build -- yet a single poke by the lowliest mook is instant death. Crack out that Konami Code, people!
 * Except in the original Japanese versions, where you get three hit points per life. Since, like, forever. The option's never even once made the transition. If the Konami Code still works in the Japanese version of Contra, that'd be like having 90 lives!
 * 2D Ninja Gaiden titles.
 * Smurf Rescue is famous for doing this with, among other things, picket fences and tufts of grass.
 * In the original Rolling Thunder, touching an enemy causes you to lose one of your two hit points. In Rolling Thunder 2 onwards, however, touching an enemy simply knocks you back without any damage.
 * Seen in Car Battler Joe, but only in the first battle as your car isn't weaponized.
 * Everything in Magical Whip Wizards of Phantasmal Forest will damage you from any direction for the same amount of damage. It doesn't matter whether it's a dragon, a pumpkin, or the lance of a knight.

Arcade Games

 * Anything that moves in the Glider games can cause Collision Damage (almost always fatal), which can also result from crashing into many kinds of immobile objects, such as furniture or the floor.
 * The Dragons Lair NES game, as The Angry Video Game Nerd pointed out. Touching a door could kill you. In one hit. In a game with a life bar.
 * Averted in in the 2D shooter Mars Matrix, in which your ship will simply fly on top of an airborne enemy instead of crashing into it. Due to the game's scoring and weapon powerup system revolving around chaining together cubes that come out of destroyed enemies, this feature is a necessity.
 * In Bubble Bobble, if Bub or Bob touches any enemy that is not encapsulated in a bubble, he will die comically and immediately.

Driving Games

 * Pole Position, one of the first Driving games, had this in spades.
 * Truth in Television — Have you ever seen what happens when open-wheel race cars bump into each other at 200+ mph?
 * In F-Zero GX, touching certain things in the course scenery will blow your machine up into pieces, even if the object is otherwise non-lethal to the touch or you touch it at a snail's pace.
 * The collision physics in Track Mania are especially brutal. In a turn, if you bump the inside barrier you'll often go flying into the other barrier. The cars and track seem to be made from rubber!

First-Person Shooter

 * In Halo Combat Evolved, vehicles moving past a certain speed (which is very very low) do 10000 damage to whatever they hit. The Master Chief has 75 shields and 75 health.
 * Sword lunges at a wall can kill the user.
 * The Halo 3 beta had a form of this, wherein players who set the characters' speed as high as it would go had them running at super-fast speeds and pasting themselves on anything they ran into.
 * Some recent games (usually ones with advanced physics engines) have brought this trope to next-gen gaming. In Crysis, for instance, you can take damage from sprinting into any inanimate object. Which leads to the Super Soldier protagonist dying from collision with a dumpster. In a nice subversion, your enemies are also affected by collision damage, so you can take down a KPA soldier with a well-placed chicken to the face.
 * Super-sprinting into a tree and dying is possibly the most humiliating thing ever.
 * Section 8 also has this with the Overdrive ability. However, damage to yourself when running into things is minimal. Run into an enemy, however, and he instantly dies. And you get an Achievement!
 * In Battlefield 2 and 2142, players can be killed if they are crushed between a vehicle and stationary geometry. Acceptable. However, the same fatal damage is applied if the vehicle is parked, empty and motionless next to a wall, and the player walks in between. The game engine sees that the space between the vehicle and the wall is less than the size of the player, and applies indiscriminate logic. Death can also occur if you are beside a tank, but you happen to touch any portion of the kill zone (immediately beneath the treads) exposed by the ground's uneven surface.
 * In Borderlands, a vehicle driving at any speed will disintegrate any enemy it comes in contact with. However, enemies killed in this fashion earn the player considerably less experience points than ones killed with more traditional weapons.
 * Running into larger enemies, like bosses or Badass enemies, may destroy the vehicle (and you, subsequently) if you try to run them down.
 * In Duke Nukem 3D, if the player decides to venture too close to any of the bosses, in other words touching them, at the end of each episode, he'd be killed instantly regardless of health. However, this only applies at a certain height; at ground level the player would die instantly but if he'd be suspended in midair, by using the Jetpack as an example, while touching any of the bosses from the torso and above no damage would be inflicted.
 * In Nightmare House, the player is encountered by shadows that do not move. If the player touches them, they lose 5-10 points worth of health.
 * In Dark Forces 2, collision damage was applied to the player in any direction so long as he was moving fast enough; long falls naturally damaged you, but Force Jumping into a low ceiling or running into a wall with Force Speed also did damage. Jedi Knight II and Academy did away with this, instead opting to place multiple Bottomless Pits in nearly every level.
 * The final boss of Blood, Tchernobog, will instantly eradicate the player upon contact similar to the bosses found in Duke Nukem 3D.

Maze Games

 * Even older than the Donkey Kong example is Pac-Man. One touch from a ghost monster caused the titular character to shrivel up and evaporate, but with power pellet, the tables turned, allowing Pac to chomp the baddies.
 * Speaking of Donkey Kong, in the NES version, you can actually commit suicide nearly the instant you gain control of Mario by running to the left. Mario will die when he touches the oil drum, before it's even set on fire.

MMORPGs

 * In direct defiance of the fact that this trope is supposedly not seen in RPGs, World of Warcraft has one of these: the infamous "frogger" encounter in Naxxramas. Green oozes lazily slink across a hallway. Your party is on one side of them. You and your party need to get to the other side. It's harder than it sounds, since any lag at all will throw off your timing. The frogger hall has claimed many lives.

Multiple

 * A booster cartridge (like the Game Genie or Knuckles) was once sold for the Commodore 64 which eliminated sprite collision detection on any game plugged through it into the C64, making the player character effectively invulnerable.

Platform Games

 * A specific platformer example is - what else? - Super Mario Bros, where even the lowliest Goomba could kill you by running into you. Getting hit with a power-up active cost you the power-up but let you keep going. And then there's the Starman powerup....
 * All Mega Man titles.
 * This is one of the main reasons why Top Man's weapon is the worst in Mega Man history in the eyes of many fans. You couldn't get close enough to damage enemies with it without them damaging you also, unless the attack kills the enemy.
 * Special mention should probably also go to the Doc Robot fights in 3, namely Quick Man. To wit, the best strategy for winning the fight meant actively trying to get hit by his boomerangs - which did only minor damage - so that the resulting Mercy Invincibility would protect you from the inevitable collision damage from an enemy much faster than you that would otherwise kill you in 2-3 hits.
 * Mega Man Powered Up allows you to play as the Robot Masters after unlocking them. When you do so, a Wily-built Mega Man copy serves as a replacement boss for your character. And you take damage when you touch him. Hmm...
 * A more amusing example was perhaps Super Metroid, where Ridley's sprite was given almost comically diminutive wings that amazingly still provide him with the ability to fly, because if they were the proper size, the impact detection for collision damage would make him impossible to get close to without being struck by them.
 * Metroid is also notable for including the Screw Attack, a permanent upgrade that lets you reverse collision damage back at weak enemies.
 * Touching Mooks in the Kirby series of games would result in both the player and the enemy taking damage.
 * In Kirby Super Star, Kirby has a "guard" technique to reduce or neutralize damage from attacks, including collision damage. Guarding while bosses are contacting Kirby can cause them to slowly take collision damage instead. This was Nerfed somewhat in the DS remake.
 * In Kirbys Epic Yarn, collision damage is removed altogether, allowing to ride on enemies and bump into them.
 * If Commander Keen touches an enemy or an environmental hazard, he assumes an agonized facial expression and falls entirely off the screen.
 * Donkey Kong Country Returns uses a somewhat interesting variation: while pretty much everything in the game deals basic collision damage straight-up, there are a few enemies that play an attacking animation when DK or Diddy touches them (such as Tikis biting them).
 * In Symphony of the Night, when Alucard first enters the castle, if you fully unequipped your gear, you could use Collision Damage to fly so far back it was possible to skip the room with the Death cutscene and keep all your equipment. This does, however, require a cheat that cuts all stats but Luck (which turns up to 99).
 * At several points you have boss battles against human characters, and the key to beating them is recognizing that this trope does NOT apply, so you can just run straight past them to dodge their attacks.
 * Sonic the Hedgehog reverses the equation and smashes through enemies when he's spinning.
 * The Sonic Boost move introduced in Sonic Rush Series and brought to glory in Sonic Unleashed is a more precise example. Sonic's spin needs to watch the spiky bits of enemies, but the Boost goes straight through every unguarded enemy.
 * The older Sonic games also play this straight, however, to the point that the final boss in Sonic the Hedgehog 2 will kill you if it steps on the very tip of your toes. Apparently, Sonic's oversized shoes can be fatal if pinched.
 * Almost everything you touch in I Wanna Be the Guy will kill you.
 * Played with in some of Taito's older games: in The Fairyland Story, the Cute Witch Ptolemy doesn't die if she stays on her enemies' heads (until they jump, anyway) and can actually use them as means of transportation. In The Newzealand Story, only enemies with spikes could kill the main character by touching him.
 * The Rayman games (at least the non-Rabbid titles) have this.
 * The horrendous ostrich-riding level on The Lion King where you had to jump rocks and duck branches or else have the ostrich stumble and therefore logically cause the lion cub on its back to immediately die. Oh, and if you were jumping off said ostrich's back at the time, the stumble would mean that you touched the ground. And died. Not a good sign, considering you're meant to grow up to be king of this, and the ground is lethal.
 * Be careful when playing Lyle in Cube Sector, you can easily damage yourself with your own cubes. Wait for them to stop moving.
 * This is rather prominent in Banjo-Kazooie and its sequels, even though most enemies have actual attacks and attacking animations. As a matter of fact, in Banjo-Tooie's Terrydactyland level, after becoming a baby t-rex, the bargasaurus enemies won't attack you and you can even talk to them, but, confusingly, they still do contact damage. Another similarly confusing example is that, if you approach Mingy Jongo as any character other than Banjo and Kazooie together and touch him, you will take damage despite the fact that he's sleeping.
 * Braid. Touch an enemy and you can see Tim grimace in pain as he flies off the screen, though you can also Goomba Stomp them to jump higher.
 * Ogmo from Jumper series is just a suspectible to this as getting impaled, being electrocuted, burned or shot. Deaths by a contact with an enemy (boss or not) are counted as being "bossed".
 * Crystal Caves not only uses this, but there are two enemies (a pink snake and a green thing that looks like a jumping cactus) which leave behind corpses when they die, and these corpses still do Collision Damage. In several levels, it is very important that you kill them when they're in exactly the right spot (where you can jump over them) or else they'll block your way, dooming you to take damage.
 * Secret Agent. A minor cute fact: the ceiling fans look just like decoration, but will also deal Collision Damage when jumped into.
 * This happens in the Blinx the Time Sweeper series, but it's pretty fairly balanced by the fact that the good targeting system makes it very easy to snipe enemies.
 * Played straight in the entire Wonder Boy series except Monster World IV, where only enemies that look painful (on fire, for example) hurt to touch.
 * Journey to Silius takes this to its logical conclusion by featuring land mines that don't explode. Touching them just damages you.
 * In Jazz Jackrabbit touching an enemy will result in a lost heart. In the second title you can slightly avoid this by hitting them with a buttstomp, an uppercut (Jazz) or a karate dash (Spaz).
 * Ecco the Dolphin, which could get really annoying in levels with a ton of jellyfish or sharks all over the place.
 * In Miner 2049 er, the justification for the mutant organisms being harmful to touch was that they had absorbed a high level of radiation in the mine.
 * In Escape from Camp Deadly, touching the escaped lunatic instantly kills you even though he's tied up. Also, in one cave there's a skull you have to shoot to turn it into a 1-up. If you instead touch the skull, you die.

Puzzle Games

 * The help file which accompanied the old (and highly addictive) puzzle game Chips Challenge in its Windows incarnation attempted to justify this by describing Chip as a fragile fellow. Fragile indeed, as death-bringing enemies included paramecia, bugs and balls.
 * Played straight by Skulls and Armas in Adventures of Lolo, but averted by all other enemies, who either have long-range attacks or just can't kill you (directly, anyway).

Role-Playing Games

 * Parasite Eve has this for touching any enemy in battle. Aya will suffer Scratch Damage.
 * The Ultimate Chimera from Mother 3 is a perfect example of this trope. Any small physical contact will result in the player and his cohorts instantaneously being mutilated and killed.
 * Earlier Ys games played this straight and inverted it -- getting hit by enemies causes damage, while damaging them involves making the protagonist, Adol, run into them at an angle.

Shoot Em Ups

 * The Game Gear game Tails Skypatrol. Contact with enemies wouldn't kill you; you would simply spin out of control and begin crash-landing, but you could recover with good timing. Contact with a solid surface, though, was instantly fatal. Which is odd, because flying into ceilings or walls - or, God forbid, walking - doesn't hurt Tails at all in any other game.
 * In some Psikyo STGs, notably the Strikers 1945 series, collision damage would only make your ship power down a level instead of instantly kill you like a bullet would. Players could abuse this to milk the appearance of targets containing powerups for extra points during boss fights or to control the game's rank.
 * Similar to the Psikyo shoot-em-ups, Triggerheart Exelica will not penalize your life counter if you collide with an enemy ship -- but you lose medals and can possibly alter your score, difficulty, and ending, just as losing a life can.
 * Metal Slug plays with this. Touch with mooks? Kill them with knife. Touch with tanks? You're dead. Or when they rush you anyway.
 * Touching tanks is only lethal when tanks are moving - you're run over. Touching spiky bits also kills you unless you're in a METAL BOX.
 * NARC provides a notable reversal of this trope. You actually get more points for "busting" enemies (by touching them for a couple of seconds) than you do for killing them.
 * Action 52 is infamous for having spectacularly bad (and inconsistent) collision damage in its shoot-em-up games, to the point where it is arguably their greatest flaw. In Action 52, this is saying something.
 * In Streemerz, even touching money bags causes damage.
 * In Atmos Quake, the flaky collision detection makes the last stage impossible to beat.

Simulation Games

 * In SAS Combat Simulator on the Amstrad CPC, upon starting the game, you were immediately swarmed by vast numbers of enemy soldiers. Your "SAS Commando" would instantly die if he touched one of them. (The fact that they also shot at you wasn't helpful either). However, part way through the first level, you could get a jeep powerup. Not only was this "jeep" a virtual tank, that made you immune to bullets, the collision-damage was reversed: now enemies died if they ran into you (even if you were stationary). But if you were hit by a grenade (or completed the level), you lost the jeep. This resulted in the most uneven difficulty curve ever seen.

Non-Video Games

 * Referenced in the Sprite Comic/PixelArtComic Kid Radd; all enemy sprites have a power called the "Touch of Death".
 * And played with. What happens when you bring the Touch of Death into a fighting game? Hilarity Ensues.