I played for long enough that I developed a bit of a strategy (high score 1558), and its really fun! But I'm not sure if my strategy was what was intended, because I barely used the blue asteroids. I started by getting a lot of speed, and then just dodging the big asteroids. If that wasn't intended, I would do things like add different types of asteroids and upgrades and other things that would add more replay ability.
Also, did you make this with raw OpenGL? Because its very impressive if you did.
Overall, amazing game!