I used to own a Space Duel cocktail cabinet, a vector game that deserved to be much better known. Think of a color version of Asteroids with 3D spinning objects and other cool enemies. It has a two player co-op mode where each player's ship was chained together, so one person hitting thrust would propel the other as well. The game's difficulty level was spot on, and it made for some of the most intense gaming experiences I've ever had. Good times.