Released: 1988, NES/Famicom
Super Mario Bros. 3 was the last main-series Mario game released on the NES. The game introduced such beloved concepts as the Koopa Kids, Super Leaves, and Tanooki Suits.
Fifteen unused levels are tucked away in the game, only accessible through codes and hacking. Along with those levels are unused enemies, graphics, stage palettes, and two unused minigames. There's even a debug menu!
And in addition to all of that unused content, there are a variety of differences between the Japanese and International versions of the game. The two international revisions contain some interesting differences, too! There's a lot to know about Super Mario Bros. 3.