If you can beat all the Bosses in the game without using any lethal force whatsoever, then you can unlock the following camouflage.

Animals camouflage - reduces hand shaking when aiming guns
Cold War camouflage - some enemies hesitate when shooting
Fire camouflage - fire damage reduced
Hornet Stripe camouflage - keep hornets, leeches, and spiders away; can tame hornets
Snake camouflage
Spider camouflage - stealth increased while stamina is reduced