Nice to see others remember it. I - unfortunately - only had the demo around 1994 and used to sit and use the missile cheat on myself. Got an emulator around 2003 for the amiga and got the actual game, played it through. Yeah what a great show. Like you say it was in so many ways a 'complete' game for its time: minimal bugs, good gameplay, regenerating maps, new challenges.
Nothing like getting the nuke near the end and vapourising a few asteroids before sending your fleet in.