I think it's a great concept. I liked how bosses became regular enemies in the following stage. The art and animations are pretty good, and I most liked the frog boss, I thought it was really creative.
I encountered a bug where the frog swallowed Shinmy and both of them disappeared and the stage stopped. I think that maybe the frog swallowed her just as it was defeated. I had to restart, but other than that the game ran flawlessly. Great work as always Kit & team.