This was a really nice and polished experience :) It felt really nice to play. My highscore was 1310, how did I do?
I think I missed a sense of progression. Maybe the one of the enemy types could spawn only after you play a bit? Or the amount of enemies that spawn could increase? Just spouting some idea :)
It took me a run to understand that the gray boxes also damaged me, but eventually I found out.
Great job! Thanks for making it.