Cool, good idea, made it to the first boss so far (score 59), but it's really difficult.
One issue I have that really needs fixing is the readability of the game. Which means it's super hard to see the dark bats in front of the dark background. If that is intended, then okay, but it feels a bit like the art was put first and gameplay second.
Yeah, and sound would be huge, of course!
Anyway, good job, it's quite entertaining already!