Megawarz is a cracking game derived from Asteroids.
To return to Earth you have to visit seven planets. Each has its own, increasingly determined nasty alien hordes to contend with. I *hate* to admit it, but I only got as far as Neptune.
And it wasn't for lack of trying. It takes a lot of skill to manoeuvre the sensitive spacecraft, without sending it flying into collision with a Baddie.
That's my excuse and I'm sticking to it. Pure addiction - I loved it!