Super Nantucket World by fome82
Mario and his best friend are having slight differences and things get out of hand. But don't worry, there is a happy end!
This hack contains 8-ish levels and 1-ish good jokes.
Difficulty: I would say not too difficult. There's some things like jumping off of a throw block while grabbing it at the same time, but it doesn't get much crazier than that. There are two forced deaths (one of them seen in the screenshot), so go easy on the savestates. Also, don't go easy on the savestates!
Good luck! :)