Subsystem Damage

Subsystem Damage is the opposite of Critical Existence Failure. It is when individual body parts can be targeted or damaged, or when physical effects impede your character, such as limping or shaky aim.

Subtrope of Multiple Life Bars. See also Cognizant Limbs, for the Boss Battle variety.

Arcade

 * Phoenix has attack waves where the player's spaceship is threatened by a flock of large birds. They can be killed by a shot to the body, or damaged by shooting their wings. The wings regenerate after a few seconds, giving skilled players a chance to rack up lots of points at the bird's expense.
 * In Bosconian, the goal is to destroy several space stations in each wave. A station can be blown up with a single direct shot to its core, or the player can attack the six pods around the station's perimeter, which progressively disables the station's weapons. Once all six pods are destroyed, the station blows up anyway.
 * The arcade weapon-fighting games Time Killers and Bloodstorm, both by Strata, both have a feature that allows the player to target and sever one or both of their opponent's arms. Time Killers also gives players the possibility of lopping off their opponent's head (resulting in an instant victory), while Bloodstorm removes the beheadings but adds the ability to cut off the opponent's legs at the torso. The opponent can continue to fight without arms, and even without legs, but any attacks or special moves requiring the use of a missing limb cannot be performed, and legless opponents can barely move.

First Person Shooter

 * Deus Ex has separate health for each body part of an entity. As each is damaged, a corresponding change occurs: if your arms are hit you can't aim as well or use two-handed weapons, if your legs are hit you can't run (or you can only crawl if both are "dead"), if your head is hit your vision becomes murky. You can also choose to heal individual body parts.
 * SiN had different armor points for legs, torso and head.
 * XIII has a peculiar example in which armor is destroyed first by damage in a somewhat locational manner. Since you can loot armor from fallen foes, it becomes imperative to go for clean headshots when looking for intact body armor, and silent takedowns for helmets.
 * G-Nome, a game about Humongous Mecha, tracks damage to the various parts of your mecha. These being bipedal or quadrupedal vehicles, losing a leg is as immediately fatal as losing the cockpit.'
 * Perfect Dark: This could be done to the guards. Hitting a limb tended to worsen their accuracy and running speed, and could even cause them to drop their gun.
 * In most of the Ghost Recon and Rainbow Six series, getting hit in the limbs will incur some very serious penalties. Getting hit in the head or center mass usually results in a One-Hit Kill.
 * Soldier of Fortune allows you to damage and destroy individual body parts in gory detail. The player is still subject to Critical Existence Failure.
 * Occurs with the player's interface in Halo: Reach's "Lone Wolf" epilogue.
 * The Left 4 Dead series has a system where from 40-100 health, your character runs normally, from 2-39 health, you begin to limp and move more slowly, then at one HP, you're reduced to a snail's pace limp.
 * The Terminator 2029 implements this with the various systems, in addition to standard health. They get fixed using an autorepair system.

Real Time Strategy

 * Cortex Command: Since all of your units are machines, the game allows your characters to be almost fully dismembered and keep on ticking. Lose an arm? No more two-handed weapons. Lose a leg? Hop. Lose both arms? Ram into the enemy. Lose both legs? Use your rocket pack to get around. Being dismembered even makes you lighter (good for flying) and smaller (good for mining.)
 * Dwarf Fortress does this for every living organism except vermin, tracking damage on down to individual fingers, toes, organs, and even nervous tissue. In certain earlier editions, without taking into account surrounding tissue. It was at one point perfectly possible to take both of someone's ears off with a single arrow without hurting the head in-between.
 * Which is why sponges are practically impossible to kill in combat - they don't have vital organs. A single Giant Sponge can flypaper a whole invasion of zombies just by sitting in a pond near their way - they could claw at it forever.
 * Homeworld 2 both uses and subverts this. Capital ships have subsystems like engines and guns, but they also have a Hit Points meter, depleting which causes Critical Existence Failure regardless of the status of their subsystems.
 * Spellforce: Critically injured characters have reduced speed, making it easier to catch up with them when they try to flee.
 * Vehicles in Company of Heroes can have their engines or weapons damaged and destroyed before they die but they can't be specifically targeted.
 * Hierarchy Walkers in Universe At War have individual hardpoints that can be attacked. Only by destroying all the hard points blocking the core and the core can they be destroyed. Also, the attachments on hardpoints (such as turrets, production enhancing upgrades, and repair chambers) can all be individually targeted.
 * Star Wars: Empire At War: In the space combat portion, most capital ships and space stations have targetable subsystems for almost any system: each individual weapon, shield generator, engine, and hangar. In fact, the only way to destroy a ship is to destroy all subsystems. The ships show realistic damage when subsystems are blown up. Normally, ships have to take down shields first before targetting subsystems, but torpedoes and mass drivers easily pass through shields.
 * Mon Calamari M80 cruisers are unique in that they don't feature a targetable shield generator, meaning the only way to take down its shields is the hard way. Interestingly, Admiral Ackbar's flagship Home One does have a targetable shield generator, likely a balancing issue.
 * Star Ruler uses this: Weapons, armour/shields, engines, "support" etc. are all put together on a blueprint and can be individually damaged to put out of commission.

Turn Based Strategy

 * The Front Mission series gives each mech separate Hit Points for their body, left arm, right arm, and legs. If an arm dies, you can't use any weapons equipped on it and if the legs die movement is limited to one square (visually they appear badly damage rather than completely destroyed). If the body dies though, the entire unit dies, which tends to make shooting the other parts a waste of time. Unfortunately, you have no control over where your shots hit, although certain skills can make it more likely.
 * Actually, aiming for limbs CAN be useful, at lest in Front Mission 3, as if you destroy several of them, enemy soldiers will sometimes surrender, allowing you to capture their machine. You can then either sell it, let one of your characters use it or split it into parts which can then be equipped on your other machines.
 * In Front Mission 4, you can often stop snipers and Bazooka Mechs by destroying the arm holding the gun, and those Arms have significantly less health than bodies do. Destroying the other arm reduces the mechs accuracy.
 * The highly contested]] Third-Person Shooter Re Boot actually retains this system, albeit simplified. Destroyed parts reveal their (inexplicably indestructible) skeletal frame and any attached weapons take a massive hit to their performance. Destroyed legs cause Wanzers to sort of waddle around at a snail's pace unless they use their boosters. On the plus side, deliberately shooting a part is now fully possible (and recommended, especially with the Bullet Time mechanic)- meaning that skills that used to improve chances of hitting certain body parts have been removed or altered and every enemy now fights until its torso (and hence the entire machine) is destroyed.
 * In the rare case that an X-COM soldier hasn't been instantly killed by whatever hit him, the body part that wound up getting hit suffers from this. Though damage may be spread across the head, torso, and individual arms and legs, the most common malaise is sending a Red Shirt's accuracy even further into the toilet.
 * The Earthsiege-universe computer game, Cyberstorm used this for your mecha's dozen or more systems, generally reducing performance in a linear fashion as damage accumulated. The enemies in single-player did not have subsystems until Cyberstorm 2... where your giant cannons, once quite effective at killing, suddenly gained an annoying tendency to "critically hit" an enemy's arm, rather than put a hole in the chassis.
 * The Star Trek Text Game, possibly the Ur Example from 1971. Warp drive, phasers, torpedo tubes, targeting computer, and sensors could all be knocked out by enemy fire.
 * Sword of the Stars allows you to knock off turrets for all ship classes, as well as individual ship sections for destroyers and cruisers.
 * When facing an Alien Derelict, you get a longer boost to research if you disarm the derelict (by blowing off all its turrets) rather than destroy it, even though the second it easier.
 * Master of Orion II has subsystem damage but not subsystem targeting. Certain weapons are specifically geared towards damaging subsystems, but this is completely random and doesn't depend on the player. Also, it is possible to send a Boarding Party on a raiding mission, which usually results in the destruction of several weapons and/or systems.
 * The Space Empires games are made of this trope - a ship is destroyed when and only when all of its components are destroyed. Though in later games, it was more like when all internal components are destroyed - if you used armor piercing weapons, you could destroy a ship without destroying any of its armor! (Except in unpatched versions of the fifth game, in which using exclusively armor piercing weapons made it completely impossible to destroy an armored ship, since you did in fact have to destroy the armor as well!)

RPG

 * The Fallout series has locational targeting for both robots and living things (for example: The head, eyes, torso, arms, groin, and legs on anthropoids.) Accuracy, damage, and critical hits are affected by which body part is attacked, but the health of individual body parts aren't tracked. Attacking some extremities will result in an injury (limp, blindness, etc?) which can't be healed without the services of a surgeon.
 * Fallout 3, on the other hand, does track damage to body parts. And they can simply be healed with stimpacks (which your average player tends to stockpile, but your average NPC doesn't) or by sleeping in any bed.
 * Fallout: New Vegas combines tracked body-part damage with permanent crippling (with Hardcore enabled) but provides certain items (the uncommon, but craftable, Doctor's Bag, and the adictive chem Hydra) that will restore limb condition without the help of an NPC doctor. With Hardcore disabled, gameplay is the same as Fallout 3.
 * Fable II has elements of this - such as shooting an enemy's weapon out of their hands, or doing a headshot (or Groin Attack...).
 * Hybrid Heaven, as well.
 * In the first Kingdom Hearts game, one type of Mook that would appear comes in the form of a flying pirate ship commandeered by a Heartless. While attacking it normally plays the Critical Existence Failure trope straight, its cannons, mast and back propellors can also be targeted and destroyed, impacting on its performance (it will sometimes even shake violently, leaving it open to attack while the pilot employs Percussive Maintenance).
 * In Kingdom Hearts II: Final Mix+, Vexen's shield has its own HP bar. You're actually forced to destroy it first, as you can't harm its owner before you do. The shield will eventually respawn, though.
 * Lost Souls MUD has limb-based hit points, and you can get mental disorders from being smacked in the head.
 * Vagrant Story does this for Ashley and most enemies.
 * Wild ARMs: Second Ignition had this in boss fights. While you could just kill the boss right off, taking out the subsystems would net you extra experience, and would limit the number of attacks the enemy could use. Unfortunately, the attacks that were left tended to be the boss' hardest hitters.
 * Colosseum: Road to Freedom; part of the HUD showed a figure, which would start out colored green. If the hero was attacked on his right arm, the figure's arm's color would change, from green to yellow to red. If a leg was hurt beyond red, the hero's speed would decrease dramatically. If it was the arm, he could no longer attack or defend with it. Lose too many use of limbs, or lose the torso and head, and you'd lose the match.
 * Dead Island zombies can be hit in the head, torso, abdomen, and upper or lower sections of both arms and legs, all for different amounts of damage and crippling them in a multitude of ways. Taking out the legs of a fast zombie or amputating the arms of a brute zombie are often the best ways to kill them. Headshots, of course, do the most damage, but can be extremely difficult on a weaving, ducking, running/stumbling zombie... and the more powerful zombies can take several headshots, so removing their arms and legs first is almost required.
 * Valkyrie Profile: Silmeria has this for enemy monsters. You can attack, and break, individual limbs and other appendages for either item farming or to reduce the enemy's effectiveness—breaking a bird's wing, for example, renders it immobile for rest of the fight, breaking weapons reduces damage, etc. Breaking any living creature's head is an instant kill regardless of remaining HP, as is breaking most creatures' backs.
 * Last Rebellion has this as an important feature in its battle system: if you targeted the right parts in the right order, you can maximize the damage you do.

Sim

 * Mechwarrior is ALL about this. Individual parts can be targeted, and the systems they contain can be destroyed. More obvious with the older versions, which were closer to the original board games where everything (heat sinks, ammunition magazines, jump jets, etc.) is tracked and has a specified location on the structure; not so with version 4, where only weapon loss and crippling leg damage are reported.
 * Leg destruction has been controversial one way or another. Earlier entries in the series allowed mechs to survive with a destroyed leg and fire weapons from the ground, but this was seen as pointless because it was usually impossible to hit anything anyway. In MW 2 they remained upright with one leg destroyed and, with functioning jump jets, were fully mobile. Mechwarrior 3 made leg destruction an instant kill, which made it overpowered as legs tended to lack armor. Mechwarrior 4 caused mechs with destroyed legs to limp at greatly reduced speed (and cannot reverse), but made it impossible to destroy mechs through leg damage, which was decried as 'unrealistic'. (This last may be inaccurate: in MW 4 Mercenaries, which is basically the same game, a mech with one destroyed leg limps; destroying the second leg destroys the mech.) Only time will tell how 5 will handle this issue.
 * Star Raiders (1979) was one of the earliest examples of this. Your ship's shields, engines, weapons, targeting computer, and scanners could be damaged or outright destroyed.
 * To be fair, the game would never destroy a combination of systems that left the player completely helpless; there would always be just enough systems (barely) functional to allow the ship to limp back to a starbase.
 * The earlier Star Wars: X-Wing had some elements of this (mainly with Star Destroyer shield generators), but it was greatly improved for the sequel.
 * Its sequel, TIE Fighter, had an even more improved system, allowing individual turbolaser turrets to be taken off capital ships, as well as nearly every subsystem. Taking enough time, one could completely strip a ship down to little more than a hull floating in space.
 * Given even more time and a fighter with strong enough shields to withstand a few turret shots, it's possible to single-handedly disable enough weapons that a capital ship can no longer hurt you. Then you can disable the engines so it sits still in space, and then you rest an object on the fire button, go drink a coffee, and return to your ship firing lasers at nothing, the capital ship now reduced to a few chunks of hull floating around.
 * The next sequel, Star Wars: X-Wing vs. TIE Fighter, implemented the same, but protects turrtes and subsystems if the capital vessel still has active shields.
 * Star Trek: Bridge Commander has this in abundance. Damage depends on where you hit and how strong you set your weapons, you can target everything down to individual torpedo tubes and phaser arrays, subsystems can be disabled but reparable or completely destroyed, doing so affects the ships's performance (an especially effective tactic is to knock out the enemy's sensor array as that renders them unable to target you and return fire), and the 3D models show realistic battle damaged, to the point where you can punch holes all the way through or lop off engine nacelles. Destroying the warp core/Power plant kills a ship/station outright even if they are probably over 50% percent integrity
 * Star Trek Starfleet Command lets you knock down an enemy's shields and beam commandos on-board to knock out subsystems. Ships generally don't blow up until they've lost so much functionality that they're reduced to drifting pieces of junk.
 * Free Space and Freespace 2 allow it both ways, and have specialized weapons just for this purpose. You can even have your own radio shot out and be unable to call for resupply/repair, and incoming transmissions/dialog will be garbled and distorted. Individual batteries on capital ships can be taken out if they are harassing you, or entire operational systems completely destroyed. However, the trope is averted in the sense that most ships have Hit Points independent of their subsystems, and blow up when those are depleted regardless of any other damage done to them.
 * Actually, the Hit Points are an indicator of hull integrity as a whole. Damage it enough, and explosive decompression leads to Explosions in Space
 * The obscure DOS space flight sim Star Rangers actually allows your ship to take damage to specific parts of subsystems - in particular your maneuvering thrusters (eventually making it so that you can't turn to the right, for example).
 * Wing Commander: Available for the Player Character ship, since the very first game, where you could lose subsystems that hamper your performance but don't kill you outright; some of the damage can be repaired by auto-repair systems if given sufficient time... unless that, too, was destroyed, in which case you were hosed. Losing a gun, though, wasn't fixed until after you returned to base.
 * Starting with Wing Commander III, capships were given individually targetable turrets, and in Wing Commander IV one of the Speradon missions involves destroying the engine exhaust ports on a carrier in drydock as part of an effort to keep it from escaping.
 * In Prophecy and Secret Ops, you had to destroy certain critical subsystems (including, on the largest vessels, shield generators) before you could land the killing blow on Nephilim capships. Fighter craft in Prophecy, however, have a single "core" statistic analogous to Hit Points; if that's depleted they go boom no matter what subsystem damage they've taken.
 * In Tachyon the Fringe, the player is able to target and destroy capital ship subsystems, but they barely count towards the overall "health" of the ship. They do, however, perform vital functions (e.g. Deflector Shields, weapon generators, turrets, engine power plants). For convenience (if not for realism), these systems themselves are on the outside of the ship and are completely unshielded. This allows even the weakest fighter to take out a cruiser without too much trouble.
 * In Nexus the Jupiter Incident, each ship bigger than a fighter/bomber has subsystems that can be targetted with lasers or fighters. As a rule, lasers don't do much damage to Deflector Shields or the hull with a few exceptions. These subsystems include engines (primary and secondary), power plants, FTL drives, shields, and weapons. Alternatively, the hull can be damaged with Magnetic Weapons and missiles sufficiently for the ship to be considered lost, starting the evacuation of the crew.
 * In Starlancer, targetting subsystems on capital ships is necessary to successfully destroy them. The affected parts of the ship actually blow up, deforming the ship.
 * The sequel Freelancer allows you to target subsystems on any ship (even a tiny fighter), but you can't actually destroy them. The fact that you can target them probably means they planned to add this functionality at some point but decided not to. Of course, this would make killing battleships even easier than it already is for a single fighter. In the campaign, you single-handedly wipe out a good chunk of the Rheinland fleet.
 * In the Flying Saucer flight simulator, your alien spaceship can sometimes malfunction in a funny way due to subsystem damage.
 * Arm A 2: Operation Arrowhead (a standalone expansion on ARMA 2) introduced this to the ARMA series, allowing damage and effects (i.e. inability to turn properly if a tank's treads are shot up). For the most part this is absent from the base game, where vehicles only have one "subsystem", the Hull itself, though helicopters can also have their propellers taken out of commission either with small arms fire or smacking into the environment during a bad landing.
 * In the flight simulator F/A-18 Hornet, all subsystems and engines can be damaged or disabled. A Critical Hit by a missile can kill you or an enemy instantly.

Tabletop Games

 * BattleTech is all about this. Not only do the 'mechs have locational damage for the limbs, three torso locations (left, right, and center), and the head, but the individual subsystems, weapons and so on that are contained within them can be damaged too. This means you can trigger ammunition explosions that tear one apart from the inside, disable the gyroscope so it falls over, or go for a critical hit directly on the pilot...
 * BattleTech is in the unique situation wherein it has both Critical Existence Failure and this. A single hit on the cockpit, or 3 engine hits will instantly kill a mech, and any given shot has a small but non-zero chance of doing this. At the same time, you could have a mech with both arms and both side torsos blown off, no armor left, 2 engine hits, a single gyro hit and both hips damaged and it will still be able to move around and keep firing if it has weapons on the head or center torso.
 * The RPG RuneQuest uses hit locations with (non-escalating) hitpoints. And unarmored person will be lucky to get out of a pitched battle missing only one limb.
 * GURPS uses fairly generic hit locations as an optional rule but then adds on different effects based on damage type. The Martial Arts supplement added hit locations like veins and arteries as valid targets. Vehicles also have a system of hit locations and spaceships get a different version.
 * WARMACHINE uses this faithfully on everything large enough to warrant it. Every Warjack has a 6 column damage chart with a variable number of ablative "armour" squares in each column. After you hack through those, you start damaging vital systems which have real penalties when they fail. After enough systems give out, the 'jack shuts down.
 * Battlefleet Gothic: The game's critical hit system is a form of this. While a Cruiser still blows up after eight arbitrary damage points, critical hits give you a chance to knock out weapons batteries, cripple engines, disable shields, or simply do horrific extra damage as bulkheads collapse and hull plating shreds in the heat of battle.
 * FATAL: In keeping with its theme of "painfully detailed awfulness," FATAL allows you to stab a man in his Fallopian tubes without damaging the surrounding organs or skin.
 * The titular tank in Steve Jackson's Ogre contains elements of this. While the typical army units die from single hits, you can target the Ogre tank's weapons to knock out its offensive capabilities, or take out its treads so it can't move. Paralyzing the Ogre is usually the only way for an army to win since it's otherwise horrendously tough and can still ram the army's Command Post to destroy it (weapons or no).
 * Ammo breaths this trope. Every physical damage has to blow at least one of the target fighting characteristics (Strengh, Agility, Combat, Aim, Sense or Reflexes) before reaching the Costitution; it works like ablative armor. Damaged characteristics (up to zero) are a pain, as they are summed to the dice throw for specific action. Zeroed Aim means crap shots, zeroed Strengh lower your melee damage, and so on. Still, even a PG with all zeroed characteristic but positive Costitution is alive and kicking (only, badly).
 * Stick Guy damages one body part per successful attack. Damage to the head or the torso is guaranteed lethal, while damaging limbs just provides penalties. Limbs can be healed by sacrificing experience points.
 * Star Fleet Battles models combat between Star Trek-like starships; battle damage is resolved by destroying randomly-selected interior systems in the target (phasers, warp engines, The Bridge, etc.) until there's nothing left to destroy.
 * Starfire represents each starship as a linear left-to-right track of systems, with shields and armor on the left and the systems buried most deeply inside the hull on the right. Each damage point destroys the leftmost undestroyed system, eating away at the spacecraft until there's nothing left. As systems are damaged, the ship can do less and less.
 * Deadlands has this, with five health levels per region. Five levels of damage will potentially destroy any region of your body, which in the case of head or torso is deadly. In addition, most armour is very specific about which regions it protects.
 * In the advance set of Formula D rules, rather than having a set of 18 wear-points (acting as standard HP), cars (if not playing customized cars or characters) have 6 tire WP, 3 brakes, gearbox, body and engine WP as well as 2 road-handling/suspension WP, should a player lose the engine, suspension, gearbox, body points, they're out of the race, if they overshoot a curve by one space and have 1 tire WP left, they spin out, start in first gear and spend a turn for turning around (if they had overshot a curve by an amount of spaces that would put tire WP in negative, they would be eliminated).
 * Dungeons & Dragons, of all places. When some developers tired of Padded Sumo Gameplay, they introduced in Player's Option: Combat & Tactics and Player's Option: Spells & Magic a variant combat resolution system where critical hits caused non-generic injuries appropriate for damage type with random severity adjusted by relative sizes of the weapon and hit creature, from bleeding to broken bones to having body parts severed/crushed/incinerated/dissolved/etc.

Other/Multiple/To Be Sorted

 * Second Sight (Stealth Based Game) and Penumbra (Adventure Game with a dash of Survival Horror) both use the most basic form, with the main character limping when injured.
 * Nova 9 from Dynamix keeps track of just about everything on your hovertank. Shields on four different sides and hull integrity to start with, but also the maneuvering jets (you may be able to turn right but not left), radar (at several levels; the first damage done to it just makes the dots jitter around, further damage makes the dots flicker and eventually it just turns into static), individual inventory slots (even if there's something loaded in them), and even your special weapons. The only system on the Raven 2 that can't be destroyed is your basic cannon, but if it gets to that point, you're probably already screwed.
 * In Bushido Blade, you can get your limbs severed, affecting your combat capabilities in the following stages.
 * The Char's Counterattack game for Playstation allows the player to target different parts of the enemy's mobile suit, with noticeable effects; destroying the head reduces accuracy, taking out the shield or left arm removes the ability to defend, blowing off a leg lowers mobility, and the destruction of any of the three removes any weapons linked to the appropriate part.
 * The Gundam vs. Series games set in the Universal Century have an ability called Revival which allows you to avoid death at the cost of a body part, taking with it any weapons or abilities linked to that limb. Several machines have this ability in Gundam Vs Gundam, most notably the black Gundam Mk-II, which loses its left arm; since it has to reload manually, this means that post-Revival you can't use anything but your melee weapon.
 * Carn Evil uses this in place of an HP count for most foes. Typically, taking off the head or blowing out the kneecaps brings your opponent down. (It's as disgusting as it sounds.)
 * Similar rules apply to a Star Trek-based Light Gun Game in which you fight the Borg. Justified, since something that's half robotic isn't likely to bleed to death.
 * Realms: In this New England- based LARP, you take damage based on what body part gets hit. Hit in the leg? You can't use that leg any more (and hopefully you have good balance). Lose an arm? Hopefully you can fight with your other arm (and aren't using two weapons or a two-handed weapon).
 * Almost every LARP use it. You can save considerable time just naming the ones that don't use this trope.
 * In Monster Labs, monsters are killed if they sustain too much damage to their torso, while destroying arms, legs and head impair their fighting (and fleeing for legs). Though if they loose everything except the torso, they also die.
 * In Metal Gear Solid 3: Snake Eater and 4, shooting an enemy in the leg will cause them to limp. Arm injuries will cause his hands to shake and decrease their firing accuracy. Headshots are always fatal unless they're wearing helmets.
 * In the Naval Ops games, your ship can lose the ability to launch aircraft if the deck is damaged. Damage to the engines reduces your speed to a crawl, and a hull breach will eventually cause engine failure due to flooding. And a hit to the rudder will make it very difficult to change course.
 * Dead Space is all about system damage as a core part of the gameplay. Necromorphs can take a huge pounding in general damage before Critical Existence Failure kicks in. However, targeting extremities can remove An Arm and a Leg quite easily. One limb removed will not stop them, but will impair their lethality appropriately (lost arms mean one less claw to rake the player, lost legs mean they have to crawl along the ground, lost heads cause them to charge while swinging blindly, etc.) and enough limbs lost will kill them outright.
 * This is a major gameplay mechanic in World of Tanks, where you can hit specific subsystems on opposing tanks (their treads, fuel tank, engine, ammo rack, etc.) and preventing them from functioning properly until their crew fixes it (and you even have a chance of incapacitating a crewman). This is especially important if your gun lacks penetrating power or just doesn't do enough damage, like if a light tank goes up against a heavy, the light tank can cripple the heavy tank until it's allies can come along and finish the job.
 * In Need for Speed Most Wanted, during a police chase, if you somehow manage to get exactly one tire blown out by spike strips, you will lose some acceleration and speed. Two or more out, though, and you are busted.
 * The DOS game Lightspeed: Interstellar Action and Adventure has an "engine room" where you can store and apply various components to Screen Generator, Blaster Turret, Spindrive, Main Gun and Thruster systems. Each time you are hit, a component from a random system gets destroyed, which can have the following effects:
 * Reduced probability of the screen generator deflecting an attack.
 * A blaster only being able to give off three shots in a row before overheating, or ceasing to function completely.
 * Loss of interstellar travel fuel efficiency
 * The main gun taking longer to charge, or doing less damage
 * Loss of engine speed
 * The closest the game comes to having your ship destroyed is when your navigator gets destroyed and you have no more in stock. It's always the last to go, though. When this happens, you have to use your escape pod to return to base, and you lose a ton of game time waiting for a new ship.
 * Many of the larger enemies in Einhander have multiple parts and weapons that can be damaged. Destroying certain parts of an enemy may bring it down, but it's safer to just go for their cockpit as it's their weakest spot. Plus, it's generally not a good idea to attack enemy weapon pods as you might actually destroy the want you want to obtain.
 * Been part of the WWE Smackdown vs. Raw wrestling games, allowing you to focus your moves on a specific area. Though this doesn't reduce opponents mobility, they are far more likely to submit via a hold that targets a badly injured area, than one that has taken no damage. Similarly, they're unlikely to get properly pinned unless there torso has been severely injured, making focusing on a specific body part a key strategy of winning quickly.
 * Some driving games, such as the Forza Motorsport and TOCA series, have damageable vehicle subsystems, impairing your vehicle's performance according to whatever has been damaged. In Forza, getting rear ended could damage your rear spoiler, or wreck your engine if you have a rear or center mounted engine. Bottoming out your suspension will quickly ruin your shocks and springs, affecting your handling. Taking side impacts will cause your alignment to get screwed up, forcing you to constantly steer in one direction to drive forwards. All of the damage except for body damage and downforce damage can be repaired in the pitstops, however.
 * The Monster Hunter series has this for its large monsters. Certain parts of these monsters can be broken to grant additional drops; likewise, certain parts grant extra attack options, and destroying or severing these parts impairs these attacks in some way if not disabling them entirely.
 * In Guns of Icarus, enemies can target different parts of your zeppelin. If your rigging or balloon gets destroyed, it causes a Critical Existence Failure. If your cargo bay is destroyed, it affects the rewards you earn for beating the level. And damage to your engines causes you to slow down and eventually stop. Part of the strategy of the game is prioritizing which sections to repair and how long to wait before repairing them.
 * In FHBG, Sneakers that have absorbed one hit can no longer crouch.