Nice Game. I feel like a tutorial is missing, I only found out about the shield via the settings.
The parallax effect is cool but actually makes the asteroids feel to move erratic. In fact at first i thought they do (being manipulated by gravitational effects or something) but I noticed they don't. But I had to stand still to find out :D
One more thing: I assumed that the music was 3rd party? If so, you might need to credit the author dependent on licence. If you made the music on your own: Good Job - please reply to me because I want to up your audio rating then!