The music choice was nice, and I like the overall idea of the game.
Some people have already mentioned this feedback I think but some i-frames would be great, and also ensuring a fair spawn of enemies. I think it would be more fun if the bullets didn't destroy each other, because it became a matter of who insists more in the correct position to be able to destroy the blue enemies. That, and also sound/visual feedback when you hit the enemies.
But other than that, a fun game! Very chaotic indeed! Good job.