Yes a crazy guy made, well is making its not completly finished yet, a mario game that has elements from Halo, Megaman and Many other games. Check out this video to see Mario kill some Covenant with their own weapons: Super Mario Fusion: Mario meets Halo

Theres also a video where mario goes through the bubbleman stage in megaman 2! Theres a demo avalable on the same youtube page tough I don't know if thats the up to date one.

p.s. How do you like my mock gamespot screenshot I made pretty cool huh?