Those levels, however, are messed up. They're broken, contain enemies that have no place within them (a Goomba underwater?!), and look completely bananas. They're the bastard children of Nintendo's most revered game, hidden away in the annals of each cartridge's aging chips. These are levels Nintendo never intended anyone to see, and the company's never really spoken about them as a result.
But guess what? Intrepid Nintendo enthusiasts have cracked a crazy secret process for unlocking these hidden levels.
Here's how to do it.