Just awesome all around, definitely the best game I've played so far in the jam. Fantastic music, gameplay, art, everything!
The only thing I would change is the ability to just restart the boss. It kinda sucked having to run through the last floor (or more if you die lol) just to get another stab at it when the later floors are so long.
Also from the image I really thought this would be a horror game but was pleasantly surprised when it turned out to be a cute platformer.