The spaceships you shoot at look a lot like a ship from the original Star Trek T.V. series, but with the front "saucer" and engines only. Also, the engines stick out from the bottom of the ship. They only appeared in profile with the "saucer" on the left.
The word "enemy" is used loosely because they didn't even shoot at you. They just appeared and wandered around the screen, waiting for you to shoot them.
