It's taken me ages to fathom this out, and after two nights, I'm still not sure I've got it right. There is a manual, but it's laid out in a very peculiar way. Details of controls come before the object of the game, and the layout of the pages suffers from not being properly typeset; very confusing and strange from the company which brought us Valhalla.
Broadly, it's an arcade adventure. You are cast adrift on an alien-built artificial asteroid. In order to stabilise it in Earth orbit, so its secrets can be studied, you must find your way around its decks and levels, recovering lettered modules from closed racks. There are seven spread around, and they must all be returned to the central racks of the controlling computer. Travel between levels and decks is accomplished using transit tubes, and these too are found on each deck. In order to either open a rack, or gain access to a tube you must dock with them, with help from your on-board guidance system.
If the manual is poor, the graphics are superb; 3-D lines in one colour they may be, but the effect is stunningly realistic as you zap your way through guardians and monitors thus rebuilding your shields. As you move towards them, static lazers raise their heads and fire! Beneath this superb view, lies your instrument panel in colour.
Complex, addictive and frustrating - perhaps because it crashed each time I used it - great graphics, great idea, shame about the lack of finish.