Like Asteroids in three dimensions, but more...
The Rek are an enemy race which have been warring with humans for years. In the latest round of battles, many human prisoners were captured. They are being held in several massive Rek prison cubes, floating in space.
Your mission: rescue the prisoners! You will be warped to one prison cube after another. In each prison cube, you must release the trapped allied prisoners by pulverizing the asteroids until you find the small, gold-colored "prison asteroids". Blow up a prison asteroid, and the prisoner will be free - he will float to you and jump into your ship.
Naturally, the Rek have prison guards. Their wall guns, guard ships and sentinel ships will attempt to stop you from completing your task.
And remember - you're in space, so there is no gravity, and there is up... don't get disoriented or you'll be space dust!