Space Nightmare is a top down railroad shooter that allows the player to select from a fleet of 3 ships. There is the Dynamite ship, which fires straight ahead and is quick, the Blaster, which is slow but fires a spread shot, and Cancer, which can fire in all directions. All ships can pick up powerups and shields.
In this game, aliens have arrived on Earth, intent on stealing Earth's supplies of copper. Thus, the protagonist is set on a mission to save Earth's economy through the destruction of the invading forces.