As said many times, the idea is awesome.
The art and audio do need improvements, but the gameplay interests me more. I think that's the part that would need attention first. The movement of the ship is clunky, and in a game, the basic mechanics should be polished first more than anything. The weird rotation angle really confused me.
If you were to make more levels, I'd suggest before making the levels, to upgrade the ship's movement a bit.
Good job, and congrats on making a game! :D Keep on fighting.