There is an infamous, hidden level in the original Super Mario Bros. called World -1 which is glitched and impossible to complete. Dubbed Minus World, it was never meant to be played, instead serving as a hidden repository for data in the game that exists off the main track. Super Mario Bros. is not the only game with this type of hidden glitch level, and recently some hacked into one of these levels in The Legend of Zelda .
The YouTuber SKELUX has recently made it its goal to explore as many NES games "Minus Worlds" as possible and begin with the first Zelda . Unlike Super Mario Bros who has Minus Worlds that can be reached in the game itself, SKELUX had to dig into the game's code to unlock Zelda . In particular, he had to bypass the game's internal mechanism to prevent players from getting out of bounds.
The map in The legend of Zelda is an eight of the 1
When he ran that problem, he could enter the bottom of the game world without the game restarting. It is at once both completely glitched out, but also stable enough that he could reasonably play through. Also, hostile sprites are inverted and objects are scattered across the screen in a random way. There are caves with vibrant rave beats inside of them, cemeteries surrounded by invincible enemy hybrids, and many mysterious trap doors, making the whole thing look like an 8-bit acid ride.
Although not meant to be functional or played at all, Zelda s Minus World is an interesting precursor to the alternative "dark" worlds of future games in the series. There is also a beautiful visual illustration of how much is happening behind the scenes. Even in some of the earliest console games, all explicit regions were deeply hidden within coded architecture.