Deus-Ex used a location damage system.. granted it wasn't realistic pre say.. but it was logical. I'd like to see something similar but a little different.
damage to an area higher in the hierachy would also effect to some degree the area's below it.
Damage to the arms would directly effect your ability to aim, espically sniping, or with automatic weapons. I think it also slowed down how fast you could perform actions like reloading, switching weapons, opening doors, and other actions that would fall under the general basis of "manipulation".
Leg damage obviously would effect your mobility. As i said. Minor damage would effect how fast you moved, and perhaps how drastic your view bobing would be (sim-limping). It'd also limit your jumping abilities, and if drastic enough reduce your movement to strictly prone locomotion.
Head damage... well duh if you didn't die somehow i think you'd be pretty fubar anyhow.
torso damage (hmm ponders thinking) would effect breathing, and would severly reduce stanima, and slightly reduce the. (recoil control, throwing distance, max running speed ect)
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Now here's where "my" system is a little unique. I try to simulate Blood loss, in addition to pure "damage". Each area of the body has it's own seperate health index. say 100pts represents a fully functioning, fully healthy area. 0 pts is a area that is completly FUBAR.
Lets take your legs for example. Lets say that you get shot in the legs with a 9mm. Ok now your legs are down to 80pts. In additon to your reduced mobility, you now have an open wound with blood loss. Blood loss would simply be a slow (right now) drain of life pts from your torso. (if your head, or torso reaches 0 you die).
As your legs take more damage, the wounds obviously get worse, and so does the rate at which you loose blood. (not to mention the more reduced mobility). Now the unique bit about this system is that you basically can't kill someone by shooting them in the legs or arms over and over. But the more damage the legs recieve the faster that person will bleed to death.. and if we allow damage to go into the neagtives, you can have some serious blood loss leading to a realitic and timely death.
So for example if you got robar'd in the leg. You wouln't immediatly die. You'd instantly have a useless leg, with a huge wound (just like in real life). The severe blood loss would quickly siphon life pts away from the torso. (there by reducing your stanima, and your breathing, making it difficult to aim) as your torso's life pts reach a certain level.. you go into shock. Your breathing is extreemly erractic, and your essentially dead meat. (why not say the character is dead already?) at this time you probably only have a few seconds left. maybe long enough to spray down an area with automatic fire.. maybe long enough to give out a few more commands, or msgs on enemy movement. Maybe long enough to pull a pin.. (you'd be too weak to throw it beyond a few feet though) or maybe push some buttons or whatever to complete the objective of the mission.. who knows.. point is that you have a few seconds to do something.. though it probably wont be effective in terms of combat.. but maybe your msgs might save your team.