The original “Super Mario Bros.” is more than just the 32 or so levels you’ve played. The original “Super Mario Bros.” actually has hundreds more levels. Hundreds!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 forgotten 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.
It’s just one of many of the hidden levels contained in “Super Mario Bros.,” and it’s perhaps the most widely known. You can reach it by performing an awkward backwards jump in the game’s second level, 1-2, like so:
Source Business Insider