This is a "Galaga" style vertical shoot'em up with a few unique twists that make it interesting. You pilot a single fighter ship against an armada of enemies (sound familiar?). There are 2 different play screens that alternate :
The opening screen uses pseudo 3-D graphics and has a large red bit of what appears to be machinery (or perhaps part of a very large spaceship) as background on the bottom half of the screen. You can move your ship around anywhere on the red background, but the black area beyond is off limits. The game opens with a large mothership craft visible at the top of the screen, but your shots cannot reach it at this point. Red UFOs quickly begin attacking you, swooping in line formations from the top area of the screen. They actually scale in size as they get closer to you (a nice effect for a 1981 raster title). By moving around you will discover that the screen can scroll upwards quite a bit, and the enemy armada comes into view if you get near the top of your area. The armada consists of several rows of ships in classic "Space Invaders" style, except for the fact that they are tiny. You can quickly blast the armada away, as you have twin shots on this opening screen, and you can have several sets of them on screen at once (it really only takes a few seconds to take out the armada). After the armada is gone, the mothership begins spewing out groups of red UFOs (who make suicide runs at your ship), and a new green ship that actually fires at you. Be sure and shoot these green ships quickly, as they split into 3 separate enemies once they reach your movable territory. Eventually the mothership will stop spewing fighters at you, and the entire screen will scroll up (taking you completely away from your red 'home base'), and the game will begin the second wave.

The second wave pits you against the mothership directly. You will find that your multi shot is gone, and you can only have one shot on the screen at a time. The mothership has 3 areas that must be blasted away (a 'spark' on each side, and then the center which takes several more hits than the sparks do). The mothership does not flash, or otherwise provide any feedback on a successful hit, but just blast away, and eventually you will get it.
After killing the mothership the game will award you bonus points based upon how much fuel you have left and then the game will begin again with increased difficulty.