Looks gorgeous! - As others have mentioned, I sometimes couldn't get to a ring, and other times the asteroid was smack in the middle of one? (I *could* still get through the latter, but my perception of my 'in-game size' seems to say I shouldn't be able to fit through, so it might confuse players)
Mouse control seems a bit too fast, but maybe that's just my Windows mouse speed settings - but a lovely, smooth moving game! - very impressive!