Nice little game! I played several times and it is quite difficult. I never got very far. I like how the projectiles are synchronized with the music. This gets less noticeable as there are more and more enemies on the screen at the same time.
Suggestions for small improvements:
- auto-focus the retry button so I can just press enter and not have to use mouse between runs
- add some time counter or score so I can see how far I managed to get