Play with friends you know IRL :D ok now what I do is: if he has bandit skin KoS, he killed others he will prolly kill you. If he is normal survivor ask him to stop and answer. If he does it, give him supplies(not guns) fix him up if needed etc. But if he keeps running(note: ARMED survivor) i shoot him I never shoot unarmed survivors, you shouldn't either... Hope that helps..