I have another idea for the heat system, I could make it so every so often, if you are cold enough, it gets a random number between 1 and 5 (or 4) and then that body part gets turned purple. If its the right, you can't equip weapons, if its the left, buh bye left handed stuff. If one leg is gone, I'll prolly make you go slower, and if both your legs are gone, Ill make you crawl like for the landmine.
In other words, frostbite.