I can't even imagine this game CO-OP, Spending time on this great place with your friends? Mind blowing.
Making this game CO-OP will make this game gain more players and making this game CO-OP will make the gamers being able to discover this great game together. In my opinion most of the people do not want to play single-player games these days, Past days single-player was pretty fun but when the CO-OP, Online, Multiplayer has arrived, Gamers started to think that "Why would I spent time on singleplayer game by myself while I can spent time with my friends?" And thats why such a great game like this has to be CO-OP or even if its possible why not Multiplayer? Be able to make this great game, Why not able to make it Cooperative? And please think about it.