Player 1: A=turn left D=turn right W=thruster S=fire Q=shield Player 2: J=turn left L=turn right I=thruster K=fire U=shield
Gravity based on Newtonian physics, although missiles have no recoil and don't start with the parent ship's momentum, because that made it really hard to play. Concept totally stolen from a game I used to play as a kid, which I think was also called Space War.