The Earth has been invaded by an alien race named "the Squarm". The player, an elite member of the Temporal Brotherhood and in possession of the interstellar spaceship Void-Runner 1, travels from sector to sector in space in search of Time-Gates which will transport the player back in time. The goal: Finding the enemy headquarters in the distant past and destroying it.
The gameplay for each particular period of time places the player in a 6x3 gridded sector of space. The player can warp between the different areas (which are shown to contain enemy ships and/or planets) in search of the elusive Time-Gate which could be in any area. Fighting with Squarm enemy ships takes place in a 3D view out the cockpit window, and any sustained damage can be repaired by landing on the various planets, although you may of course have to battle aliens to be able to get there.