Nice music! It's a neat little game, I made it to wave 19. I have to say that I didn't find a use for the moon shield, as everything seems to be moving too quickly to use it well. The moon shot ability is situational at best, as you only need to point the moon in the direction of the enemy and they'll slam into it. It only comes in useful if they're just out of reach and there's another enemy on the screen.
All in all, a decent entry. Had fun :)