Interesting game! I enjoyed the challenge of learning the boss patterns and how they played out, and the freedom to be able to change statistics for each boss you face.
I did notice an issue where if you reduce jump height on level two, even though you can beat the boss you can actually get stuck unable to reach the exit portal (unless I've missed something!) also your stats only return to normal once you get to the shop after the boss so if you're mega slow you have to drag yourself over to it lol. Maybe the stats of the player can be reset whenever a boss is killed to fix both of these in one?
Either way very good gameplay and a nice take on the theme. Good job on your submission :)