Ok ya I can see it, lets use sanity rolls to mess around with the players vision most notable friendly targets and "kin", gore areas raise the chance of you having vision issues.
Let me further explain it as best I can
This could be implanted on any game type, CTF or team death match, there are 2 teams with 3 sides kin monster and human, Kin are well the mutated fish people or humans that are infected. Monsters tend to avoid kin love to chew on humans but if they are hurt or pissed they will go after kin.
Monsters and Kin have sanity effects on humans as well as limbless and ground up corpses.
Sanity loss has a few effects basic sanity loss is blurred vision, next is can only see the level but player/AI models, next is friendly and enemy models are swapped, and the last is you reach a kind of temp enlightenment from insanity you go into bullet time and can take 100% more damage for a set period of time.
HP would regenerate real fast on full sanity or enlighten insanity and slower on any other sanity level. Its 3 or 4 times harder for Kin to roll sanity loss is blurred vision, next is can only see the level but player/AI models, next is friendly and enemy models are swapped but if they do roll it they get it for twice as long. And take double damage, they start out with twice the defense as human players and are a bit slower.
Less than human sized monsters are easy to kill, bigger monsters are invincible-ish and wander the map looking for human food and hurt kin to eat, when one is on a enlighten insanity roll they can do massive damage to the bigger monsters.
How dose that sound?