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.
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 ageing 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.
There's one well-known secret world in the original 'Super Mario Bros.' -- it's called the 'Negative World.'
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:
The level itself is just a standard underwater level, though it's impossible to progress beyond it. Exiting the level results in a loop.
But that's just the beginning. There's a far more involved hack that enables anyone to access hundreds of hidden levels in the original 'Super Mario Bros.' You need three items to pull it off -- first up: an original 'Super Mario Bros.' cartridge:
At any point during the first level, 1-1, pull the cartridge out of the system while the system remains powered on.
BEWARE: Yes, this might break your NES, and your game. Try this at your own risk.