Robocraft is a multiplayer action game where 2 teams of robots battle each other to control virtual arenas. 

It's a bit like World of Tanks, in that you need to work together with your allies in order to take control of the map in an excellent mix of action and strategy. 

Bear in mind that one of the most interesting aspects of the game is the ability to freely create your robot using blocks (and following the laws of physics). Overall, it's a great multiplayer game.