A group of modders have been working on getting Mario playable in Sonic Generations.
The mod swaps out SEGA's speedy blue hedgehog with Nintendo's ever-grinning platforming plumber. It also includes a bunch of new music, background visuals and even new enemies from the Mario universe. For details, be sure to click through on the YouTube trailer.
Will you give the mod a go? Could Mario work within Sonic's world, and vice-versa?