Super Meat Boy

A standalone game with a few non-franchise characters shoehorned in is one thing, but Super Meat Boy goes above and beyond. The famously difficult platformer features over 20 additional playable characters, all of whom come with their signature moves and abilities, changing up the gameplay as well as paying tribute to their respective games.

It's an indie gaming smorgasbord of epic proportion, fueled by Team Meat and comprised of characters like Alien Hominid, Commander Video (Bit.Trip series), Gish, Josef (Machinarium), N the Ninja (N), the Pink Knight (Castle Crashers), Steve (Minecraft), Tim (Braid), Viridian (VVVVV), and even Tofu Boy, from PETA's lame Super Meat Boy parody-protest, Super Tofu Boy.