well..
for an unfinished game this is pretty polished. the visuals were very well made and the basic game mechanics worked smoothly.
things that should be improved :
background loop - far too short, kept seeing the same 2+2=4 thing every 2 seconds.. irritated my eyes. needs to be longer and/or better randomized.
music loop as was stated before me was a bit on the short side as well.
power ups, raising difficulty level, boss fights etc.. the basic mechanic is fine but will not keep me entertained for very long..
maybe this was intentional but it seems that when an asteroid hit my ship if I moved swiftly away I received almost no damage and if I stayed with the asteroid for the duration of the explosion animation I received a lot of damage. the way I see it it should be standard damage per hitting an asteroid. but that one may be just my point of view.
scoring system - obviously.
that about it. :) loved the visual premise and the feel of the game. definitely worth additional work.