A curious thing happened to me while playing this game. Probably a bug, but one that had an incredible effect on me!
After several attempts, I just couldn't beat the boss. So, since you can continue the game when the “You lost!” screen appears, and your character becomes de facto invincible, I thought I'd continue fighting the boss at that point, so as to see the whole fight through. So I ended up beating the boss unofficially, and then the screen very quickly alternated between a frame displaying “You lost!” and a frame displaying “You won!”
It really gave me the impression that the game had understood that I was trying to cheat, and was mocking me by saying: “Yes, you won, but we know very well that you cheated”.
In short, a happy bug that I'm delighted to have met.
There are plenty of games to try for this boss rush jam, but maybe I'll try again later to get through this one the right way.
In the meantime, well done on a well-executed submission :)