Madou at the DigitalPress forum seems to have found some graphical proof of the existence of Mr. Nutz 2, an old unreleased platform for the Sega Genesis / Mega Drive. There were some discussion about the state of the game, but if these screens are real, then it looks like it was really in development somehow:
I'm an Italian gamer with not enough free time to play as much as i'd like to and sadly not enough time to write about cancelled and beta games. Founder of Unseen64 in 2001, i'd like to sleep more than 5 hours a day, but i have to pay the bills. I'm currently working for various italian & international websites for a better User Experience & Search Engine Optimization, you can add me on Twitter, Last FM or contact me by email.