A hacker named RainbowSprinklez has created a mod for Donkey Kong Country that allows players to control Mario, specifically from Super Mario World, as he battles King K. Rool and his minions.
This modification goes beyond a simple sprite swap by integrating various Mario-themed mechanics, such as coin blocks and the ability to ride Yoshi. Players can execute classic Mario moves, including spin jumps and launching fireballs, while the music has been replaced with tracks from Mario, Zelda, and Mega Man. RainbowSprinklez, a big fan of Mario, hopes that others will build upon this work.
The hack is available for download on Romhacking.net.