It's simple: the most efficient and least risky method of survival is to kill every stranger you see (if they are alone or if you outnumber/outwit them), at the earliest opportunity. Preferably without letting them know you exist until it's too late. But why is that, you ask? The game is such that the greatest threat to your character is other players. Neutralizing other players means neutralizing the greatest threat to survival. So what can we do if we wanted to reduce the rate of KOS? It's easy: introduce an element to the game which poses a greater threat to your character than the threat of other players. Naturally some players will start banding together, randomly, to cooperate to neutralize this threat. The more threatening this new element is, the more people will work together to defeat it. What is this new 'element'? I don't know, be creative. A giant robot? Or to fit with the theme maybe even a roaming hoard of relentless zombies (hint hint)? Bottom line The enemy of your enemy is your ally.