Body Armor as Hit Points

In the context of some video games, sometimes body armor just provides a bonus to the owner's maximum Hit Points. Rather than add any kind of specific protection to certain attacks, a character wearing body armor will just gradually have it chipped away whenever they are hit, in the same manner as their usual Hit Points. If enough damage is sustained, the extra body armor may simply vanish, most of the time retaining full efficiency until it's gone.

It is not usually visible on a character, and acquiring it puts the object to use instantaneously, so the player character is never seen discarding it. This trope is, obviously, not particularly realistic. Ironically, it became popular with many "realistic" shooters because putting on body armor seemed a more plausible way of improving a character's Hit Points than having them grab a first aid kit in the middle of a firefight. Generally necessary for the sake of game mechanics, although this is less true today than it was ten years ago.

A variation of this which generally is considered to make more sense is Full-body Deflector Shields As Hit Points. After all, energy which specifically covers your entire person and uses energy to protect should be able to help protect you from anything as long as its energy supply is sufficient, right?

Possibly a bit of Truth in Television or videogames rather. Interceptor body armor for the most part stops bullets outright but breaks down after soaking up one or two hits, making it effectively a free bullet to the chest before dying card.

Compare Call a Hit Point A Smeerp. Contrast Destructible Armor, where the amount of armor is a direct indication of the user's remaining HP. Using this system rather than making armour a separate stat Armor Piercing Attacks can circumvent may help avert Armor Is Useless.

Arcade Games

 * Aluminum foil works this way in Glider PRO. Of course, you're a One-Hit-Point Wonder without it.

First Person Shooter

 * Alpha Protocol has armor that grants endurance, which is like health that regenerates.
 * Many James Bond FPS games, however Nightfire plays with this to a degree: Your armor only protects you from bullets. When you fall from a great height, your bio stats decrease.
 * Perfect Dark uses "realistic" personal shields.
 * In Perfect Dark Zero, body armor will mitigate the effect of being shot, although it will still undergo Critical Existence Failure and stop working, and is useless against melee. This actually makes sense, as kevlar vests in real life are designed to absorb bullet impact, and do nothing against a knife or club.
 * The second FEAR game.
 * Played with in the early Rainbow Six video games. Without heavy armor, the player character can go down in as little as one bullet.
 * The shields from Halo.
 * Half Life, and the infamous HEV suit. Power in the HEV suit works like actual armor. Minor things will just chip away the power, but bullets will still take off HP.
 * Played straight in Unreal Tournament 2003, which completely abstracts armour as a floaty yellow shield icon when not equipped, and otherwise as a number that will go down instead of your health when you're hit.
 * Unreal, Unreal Tournament and Unreal Tournament III also effectively played it straight. Although damage for most types of armour is divided between the armour and health, unless you were already heavily damaged when picking up a piece of armour, the armour will always be gone well before your health hits zero. The 2004 edition used a similar approach, only with the abstraction from 2003 in place.
 * Unreal II the Awakening has an interesting aversion, where the level of your shields affected their effectiveness. At full shields they'd absorb 100% of any damage you took, but below 90% or so you started taking partial damage to your health with the shields only absorbing a percentage of total damage, which got lower and lower as your shields dropped (i.e. at 50% shield strength your shields would absorb less than half of the damage of a hit). It's not uncommon to die with with your shields still at 33% or more.
 * Borderlands has the "Deflector Shields As Hit Points" variation (plus some of them actively restore health).
 * Armor in Dystopia has a certain hit point value and takes damage in place of some of your health, but it works differently. It takes double-damage from explosive weapons and half-damage from everything else. It also cannot be regenerated like health.

Literature

 * In the Lone Wolf series of game novels by Joe Dever, any piece of armor you found would add to your endurance points. Largely because combat skill and endurance points were the only stats you actually had.

Platform Games

 * Demons Crest gives Firebrand the Legendary Gargoyle morph, which effectively doubles his life gauge. In a more traditional example, the "Armor" talisman halves damage he takes. These two effects stack when used together.
 * This is how armors work in Legend of Kay. You even get an extra Life Meter (for the armor) next to your normal one.

Real Time Strategy

 * Command and Conquer Renegade also used it. Even vehicles have both types of hitpoints, but the armor is taken off first. This makes some sense for the Mammoth Tank since it ties in with their self-repair (which only affects normal health, allowing it to recover to 50% just like in the original game).
 * In Starcraft, the Protoss have the "Deflector Shields" version.
 * Armor upgrades in Dawn of War increase hit points rather than damage resistance. This is because the game engine relies on armor type to determine damage taken.
 * In Starcraft II, the Vanidium Plating upgrade adds +5% HP per armor upgrade. This also affects vehicles and spaceships, as well as soldiers. Marines also get a Combat Shield upgrade that grants +10 HP.

Role Playing Games

 * Ditto Parasite Eve II, where armor modifies your maximum HP and allows you to carry more usable items into battle.
 * In the computer game Autoduel, your vehicle's driver has 3 Hit Points at full health. Body armor can also be bought (or replaced, if damaged) at truck stops, which grants another 3 hit points. Driver health isn't affected until all 3 hit points from body armor are gone. (If 6 HP sounds puny, keep in mind that the damage scale is designed around armed, (usually) heavily armored vehicles shooting the crap out of each other.)
 * This is carried over from the original Tabletop RPG Car Wars. Body armour would give 3 extra damage points (improved versions, 6). As a side note on damage scale, what seems to be an ordinary M60-size machine gun does a base 1d6 damage.
 * As a humorous side-note, in the Tabletop RPG, you fall unconscious after taking 2 damage points and die after 3. A .44 magnum revolver inflicts 2 damage points. Therefore, if you take the rules literally, as long as you're not wearing armor, you cannot commit suicide with a .44 magnum, even if you put the barrel in your mouth and pull the trigger.
 * Knights of the Old Republic deflector shields roughly fit this (armour is the standard D20-style where it makes you harder to hit); there's a maximum damage quantity they can take, although they also have a time limit and a maximum they can absorb from any one attack.
 * Mass Effect plays the trope straight, with a third layer devoted to biotic barriers or shields. Most boss-type units in Mass Effect 2 have at least armor or shields. On Insanity difficulty, all enemies have armor or shields, and boss-type units have shields/biotic barriers, armor and finally health. Especially tough boss-type units have biotic barriers, shields, armor and health. However, huge or purely mechanical enemies only have armor, not health. Once their armor is depleted, it's assumed the last shot hit something vital and killed/destroyed them.
 * In Megaman Battle Network, the Barrier chips act like this. Each Barrier has a set amount of health, so if you have a 200 Barrier, 20 attacks with 10 damage will break it, but so will the attack with 200 damage. The only way to restore it is it get another barrier. The subversion lies in the sister set, the "Aura" chips. They can only be destroyed by an attack that is equal to or more powerful than their HP.
 * Deus Ex uses the trope and justifies it in universe. The body armor actively uses energy to deflect weapon fire. Once it runs out of power, it no longer provides any protection. The armor slowly depletes just by wearing it, getting hit makes it deplete faster.

Stealth Based Game

 * Batman Arkham Asylum also does this. Each armor upgrade adds another segment to your health bar, but does absolutely nothing to improve your resistance to damage.

Tabletop Games

 * Ablative armor in GURPS acts almost exactly like normal hitpoints (the exceptions being against attacks with armor penetration modifiers).
 * Rifts's Mega-Damage system basically replaces your normal SDC/Hit Points with the armor's MDC, given that even light Mega-Damage to a normal human will usually kill them outright.
 * Other Palladium games have body armor work as additional SDC, though it is also a slight aversion to the trope due to a mechanic called Armor Rating. It's dependent on how much of the body is covered by armor. Any strike roll that goes over the A.R. does damage directly to the character, anything under the A.R. damages the armor itself.
 * Battle Tech armor is universally like this; it literally adds extra hit point boxes to a given unit's location 'outside' the internal structure proper, which are usually not actually any tougher but have to be eliminated before any actual structure damage can be inflicted.

Third Person Shooter

 * Your character's Flak Jacket in Syphon Filter.
 * In Jak 3 and TLF, you start with around half a circle of hit points. Each armor upgrade gives you a couple extra points.
 * Oni uses the Deflector Shields version with the Forcefield item absorbing attacks from guns.
 * James Bond, yet again. In Everything or Nothing, it's implied that one hit will kill you, and your HP meter is the effectiveness of your armor. In From Russia With Love, it's played straight in that the armor is a second health bar.

Turn Based Strategy

 * Final Fantasy Tactics has no defense stat. Instead, armor just increases HP. Since you get a maximum of 2 HP per level, it's vital to make sure you have quality armor.
 * The first Master of Orion game had just generic hitpoints and shields, determined by ship size/armor tech and shield tech, respectively. The sequel changed the hitpoints into separate armor, hull integrity and system status levels, making ship design strategy more complex and interesting.
 * In Sword of the Stars all armor techs add to the health of your ships, but they also dramatically increase the chance of physical weapons simply ricocheting off the hull with no damage. Weapons in the 'Polarized Plasmatics' tree are dangerous because they negate that bonus.

Wide Open Sandbox

 * Grand Theft Auto: All of the Playstation 2-era games use this trope the same way; body armor hit points are indistinguishable from regular hit points insomuch as game mechanics are concerned, but in Grand Theft Auto IV, only being shot or caught in an explosion will take off armor; damage taken from falling, getting run over, getting punched in the face and so on bypasses it. San Andreas and Liberty City Stories also bypassed armor damage from drowning and falling.
 * In Spore, adding armor to the animal increases the hitpoints, though the increases don't stack.
 * In Eve Online, spaceships have hitpoints split into three types: Shields, Armor and Structure which take damage in that order. There are modules you can fit that will increase the hitpoints of each type, thus increasing your ship's "life".
 * In Assassin's Creed II, armor adds to your health bar. However, over time armor gets damaged and when "broken" you can't regain the health it provides until you get repairs done.
 * In Prototype. Alex has two defensive powers, a shield and armour. The shield on his arm absorbs hit points until it breaks, whereas the full-bodied armour simply reduces the damage done to him while slowing him down.
 * In the classic computer game Auto Duel, your character has 3 hit points and can buy body armor at any truck stop, which provides another 3 hit points. Unlike your body, though, the armor can't be fixed once it's shot up, so once it's sustained the full 3 points of damage, you'll need to buy new armor. (Oh, and if you're thinking that 3 hit points is a puny number, keep in mind that the game is designed around the concept of vehicles blowing the crap out of each other.)