This game is pretty awesome. I really like the art stye actually, and the music really fits it well. There a lot to love here, and you've put together a really interesting game. I love the little changes that happen during boss battles like the screen getting smaller. Such a unique game for sure.
I will say that it was a lot of information thrown at me and I found it difficult to understand what was happening. Like it changed my bullet color or even limited some colors from time to time and I wasn't exactly sure why.
But anyway, overall this game is amazing! Good job :)