Classic games, computers and gaming consoles are a source of joy for those who came of age when the titles and hardware were cutting edge commodities. Few things can transport you back to your youth faster than playing with what made you happy back in the day. For some people, playing with the games of yore includes tinkering to make something new and wonderful.
Modder Kaze Emanuar has taken the 2D level design of that older game and crammed it into the engine of Super Mario 64. Judging from the video that announced the mod, this allows the player to do all the leaping, hopping, and air flipping that a modern Mario can do while still enjoying the "classic" feel of the levels.