I stumbled upon this video on Youtube and it seems interesting. It introduces other 8-bit characters to the world of Super Mario Bros. These characters are Link (Legend of Zelda), Samus (Metroid), Mega Man, Bill (Contra?) and Simon Belmont (Castlevenia).

This game isn't just a sprite swap. Each character actually comes with its own special moves. Link can throw boomerangs, and Samus can turn into a ball and plant bombs. It's all quite cool and impressive.

I'm pretty sure there's a link to the game in the Youtube description, why not go check it out!