I think most of those ideas would be great for mods but, Two teams vs..... that my friend would have serious potential to make it in the game. Think about it: One life, competetion for resources, zombies trying to kill you, players trying to kill you, burning down others safe houses, an invisible wall so no one can run into the woods, stealing food from others, leading hordes into other players, just two teams trying to greif the others as much as possible until finally the one lone teams survivor gets trapped in a burning attic...... or whatever. I would be surprised if a team game doesnt make it into multiplayer.