after it there won t be selfish players

[West]

Well, there is always a way to let them die (no more shoting while being down), till round end (just like in CoD:WaW/BO1 Zombies). I know it's not so fair to take away from players their UP, but when we talk about reviving it's going the same way in another direction - not cool to be just forgoten (like "who cares..."). However, this method can teach players proper cooperation by the consequences. BUT there will be only problem with AFK players.

Let's just say, there is no good way to teach players how to play side-by-side - all for one, one for all.