This was a really fun game with a great concept!! Very well made!
As silly as this sounds, I was really happy to see both a settings/options menu and an exit button! lol
I think my only suggestion (and maybe it was there and I missed it) would be to toggle whether or not HP is fully regenerated each round or not. If a player has a hard run with one boss, but still wins, it feels a little unfair that the boss gets stronger AND a full health bar while I, the player, start off handicapped. That said, I do understand some would love this challenge… which is why I suggest a toggle at the beginning of a full run.
Beyond that, this was a wonderful game! Excellently done!