Tonight I played Alien Breed 2: Assault. It's a top-down shooting action game where you are trapped on a ship infested with aliens, trying to reactivate the engines. It's a sequel (thus the '2') to Alien Breed. I actually got this game for free, which is why I haven't played the first one.
Alien Breed 2: Assault
Alien Breed 2 is pretty fun, as long as you don't mind aliens popping out of the ground and walls. The only real issue I had was that the camera angles were sometimes a bit finicky.