I think it would be cool if every player had a "white flag" they could start with and could equip as an alternate to a pistol, as an initial idea. When they equip it you would know that player isn't being aggressive. You could also make it take a while to unequip so player can't just yank out / switch to a gun and blast you without a visual warning to give you a heads up. It doesn't have to be a "flag", but could be a white rag, or torn piece of shirt. People would have such things in a zombie apocalypse. Another, similar line of thinking is players could put their "hands up"(a signal that they aren't looking for trouble) in the air, with no weapon in them, or alternatively put their hands behind their head. I think that animation exists in the original game. If the hands could wave, it could be a signal, here I am, I mean no harm or I want to approach. Players could approach one another with their hands up as a sign of "peace". This is also realistic... I could see one another yelling "come toward me with your hands up so I can see your not pointing a gun at me", the other person could say "you too", "Agreed". A third concept could be that a player could have a "signaling mirror", that could be used to signal another player from a great distance. "Hey you" I can see you, here I am and the other person could wave back or pull out their white flag. It would also give away their position(see the flash). If you're willing to give away your position that also shows that you probably aren't looking for a fight and would like to approach for a discussion. I think the game is fun with teams of players, the only problem is that there isn't much of a way to signal your intentions... so players have to defensively kill each other, when in real life they could flag one another down, yell pretty far, etc... I think these ideas would allow people who want to join up express themselves more effectively, which will make the game more fun... having fun with others. It wouldn't stop players from killing one another so it takes away nothing from those players who enjoy that.