From the inlay:
A grotesque alien craft rises from the pink glow of the horizon, firing a salvo of Meson torpedoes at you. You thrust forward swooping over the surface firing your ruby laser, with a blossoming of flame and metal fragments the first alien is destroyed.
A second wave of alien ships drop at you from space ... Your fingers tighten on the controls...
This is very loosely based on the arcade classic "Defender". The differences include that you can only go from left to right, and that you are not actually defending humans on the planet surface below. You control your ship with up and down, thrust forward and fire.