This is pretty cool, and a fun way to waste some time.
I'm quite concerned that in level 32 and one previous level it seems impossible to kill the plumber with the cannon.
Also, some of his actions don't make much sense, like avoiding you when he's invincible - though it's noted that if he played optimally, especially while invincible, the game would be literally impossible.
Overall pretty great though.
...Also that ending was ... hilarious and silly as hell.