Oh, this slaps!
What a cool gameplay-loop! I'm sure I don't need to mention the difficulty. I would've loved to see some of the other mutations, but I'm just not good enough to see that content...
Personally, I think that while the animations are crispy, there needs to be more of a telegraph on the Alchemist's attacks. I'm sure with enough time you could learn what each pattern does, but given the fact that this is a short game, players need to be able to pick up on them quicker. The hitboxes also seem quite unforgiving.
I was not a fan of attacking in the direction you're moving. I felt like I didn't have enough control of my character in an already movement-demanding game.
The aesthetics of the game are top-notch, but there needs to be more attention to the polish.