>>10
when it comes to hitreg systems in games, the most complex i've seen is present in an abandoned unity project named "crisis response". this project's physiology system is very advanced and not very well optimized, so you'll need a powerful cpu (8 cores should be more than enough) to handle more than a few occupants in the building. it doesn't put too heavy of a load on the gpu though, which is pretty cool. the physiology system handles breathing, heart rate, blood volume, blood pressure, blood oxygen, physical work and physical shock, as well as concussions and brain damage. if you want to know more about how it works, i'll give out an explanation based on my observation, but the dev explains it (and probably better than i do) in this video: https://www.youtube.com/watch?v=H7BKGlj-kNs

there's an impressive amount of different hitboxes. there's one for almost every major organ (heart, lungs, liver, kidneys, brain), there's one for each major blood vessel (excluding those present in the arms, since arms cannot be targeted), there are hitboxes for sections of the spine (cervical, thoracic, lumbar) as well as for leg bones (femur, patella, tibia. the fibula seems to be absent.) and there are generic ones for limbs. there are no hitboxes for the pelvic girdle, which would be an immediately disabling hit, similar to the spine, or for genitals.

the most important aspects of the system are that:
00>a round or pellet can trigger multiple hitboxes and change trajectory within the body.
01>very painful hits and strong concussions are immediately disabling.
02>leg hits greatly slow movement and cause massive blood loss if an artery is severed or a bone is broken.
03>a single torso shot that doesn't hit any vital systems with a high-velocity rifle round is still painful enough to immediately disable most occupants, in most cases (there's a slight bit of randomness involved).
04>heart, brain and spine hits are immediately disabling, regardless of bullet mass or velocity.
05>kidney and liver hits are not always immediately disabling but cause massive blood loss.
06>lung hits perturb an occupant's respiration cycle, which in turn perturbs their heart rate and reduces their fighting ability by making physical work more strenuous.
07>non-brain headshots are usually immediately disabling because of the concussion applied by the force of the bullet. if not immediately disabling, may lead to massive blood loss by severing the carotid artery.
08>concussions disorient occupants and will fade away over time. brain damage disables occupants and is permanent.
09>buckshot absolutely shreds people. 9 pellets are fired from each shell, and each pellet is comparable in power to a .38 special round.
10>low-velocity rounds require multiple hits to disable an occupant if none of the hits are dealt to critical systems.
11>magnum revolvers do not mess around.
12>different ammo types have properly different effects. fmj just tears through everything but doesn't leave the most devastating wounds. jhp can penetrate doors, walls and sometimes armor (depending on caliber and velocity) but it will be greatly weakened after traversing an obstacle, however it has a better chance of severing arteries when it hits flesh targets in regions where arteries are present (or at least, that's the impression i get). xp is fmj on crack. rip splits into petals and causes multiple canals and exit wounds from a single entry wound, though it will also split when penetrating obstacles which makes it nearly impotent due to serious imprecision when shooting through doors or tables. subsonic is usually heavier but is slower. sometimes it's a little bit slower, sometimes it's a lot slower. for example, 9x19 jhp has a mass of 7.5 g and is flying at a velocity of 411 m/s, whereas 9x19 jhp subsonic has a mass of 9.5 g and is flying at a velocity of 302 m/s. this is not a rule that applies to every caliber. 5.56x45 is an exception. 5.56x45 jhp has a mass of 5.0 g and is flying at 850 m/s, while 5.56x45 soft point subsonic has a mass of 4.1 g and is flying at 305 m/s. this leads to an immense disparity in the energy output of supersonic and subsonic 5.56x45 rounds.
13>armor vests and helmets can catch rounds but will not prevent trauma from non-penetrative injuries.
the ttk ends up being very similar to that of insurgency (2014), where your basic intermediate caliber rifle will down an armored opponent in a single hit to center of mass.

there's also a worryingly high level of audiovisual detail to represent the damage that is being dealt. occupants will physically react to injuries, holding onto wounds, tensing up from pain, jerking violently from seizures induced by blood loss, exhibiting signs of decorticate or decerebrate posturing (not always symmetrical) or entering a state of fencing response on strong concussions, either contracting or overextending limbs on head hits, or dropping like a puppet cut loose from its strings when the brain is destroyed, and they'll cough up blood or do this really gross wet breathing when their lungs or airway are damaged. blood will leak from head orifices when related systems are damaged. when blood gets into the respiratory system, it will leak from the mouth and nose. when a concussion is strong enough, it can leak from the eyes, mouth, nose and ears, though it is not guaranteed to leak from all orifices at once on every strong concussion. consciousness is also a thing that is handled by the system. i'm not sure of exactly how it works, but it is tied to every other bodily system. an occupant can pass out from blood loss, or lack of oxygen, or a strong concussion, or intense pain. loss of consciousness is often accompanied by seizures but both reactions are independent from one another, as an occupant can be seizing up while still conscious. blood will drip on surfaces and the game uses fluid dynamics to simulate puddles. all of these systems lead to instant and very visceral feedback for hits. if the portrayal of violence in insurgency sandstorm made you feel uncomfortable (or induced in you some morbid kind of fascination), this game cranks it up to eleven.

this complex system could be stripped down and refined a bit, down to the armor, ammo types, hitboxes, bleeding and concussions, and adapted to 3d to fit into a team-based pvp game that centers on small scale (8v8 or 12v12 seems good) warfare where avoiding incoming damage and providing first aid to injured and downed team members would be rewarded by using a scoring system. teams would compete for an objective, which would be the primary victory criteria, but with a catch. there would be a secondary victory criteria, which a team would win not by having the most kills, but by being the one with the healthiest team members at the end of a round. this would give a similar feeling to that of folk racing, where racers are rewarded for being the fastest or meanest (or in this case, safest) racer on the track. unfortunately, my understanding of how games are made is fairly limited, and i find code completely alien, and making a game alone is way out of my skill set (i'm a n00b at texturing, sound design and lua, completely ignorant in other aspects) so this idea will never become more than just an idea.