You're games are awesome DiNo but I would love to see some multiplayer. Don't get me wrong I love your games, its just that I would like to play with friends. So I have a suggestion.
For this game you could make a sort of capture the flag game. A modified version, if you will. The players start on opposite sides of the map and at the center there is a flag. The players would have to overcome obstacles like gunners, turrets barrels and more to get to the center. And the fist to get the flag wins. They wouldnt have to bring the flag to a base or anything like that. The only flaw I see with this is that the players aren't directly playing with each other, therefore making the game only a little less fun. There could be two teams like Americans and Nazis or something like that.
PM me if you want more ideas.