The idea and gameplay fit the theme perfectly ! Music and sounds are great and the visuals are pretty cool ! I have faced a big issue though, I don't know if it's an issue with my screen resolution, but the projectiles didn't follow my mouse direction at all, and were always offset a bit to the right which made it almost impossible to aim correctly. In the end it didn't impact too much the gameplay thanks to the ingenious planet system but the beginning was pretty hard because of that... Aside from that, if I had to suggest one thing for improvement, it would be maybe making the asteroids drop sometimes powerups for your projectiles, I think it would help giving the game a good sense of progression.
Overall it was a fun and interesting game ! Great job !