Very cool game, I like the character and the crystal puzzles. I especially liked how that worked with the first boss. Nice graphics overall and a chill vibe.
Some things to improve on:
-The jump can't really be controlled midair and the knockback is kinda rough. Before the sonic blast upgrade there's also an extremely specific jump.
-The enemies' attacks are so fast that they're really hard to dodge. However the armored enemies can't do anything if you're right next to them.
-It's not very clear how to deal with the second boss and the hallway before it has way too many enemies, I've yet to beat the boss due to that.
A charming game overall, just quite difficult.