The Minus World () is a glitched level found in the 1985 video game Super Mario Bros. It can be encountered by maneuvering the protagonist, Mario, in a particular way to trick the game into sending him to the wrong area. Players who enter this area are greeted with an endless, looping water level in the original Famicom/NES cartridge versions, while the version released for the Famicom Disk System sends them to a sequence of three different levels; this difference is due to the data being arranged in different ways between the two versions. It gained exposure in part thanks to the magazine Nintendo Power discussing how the glitch is encountered. Super Mario Bros. creator Shigeru Miyamoto denied that the addition of the Minus World was intentional, though he later commented that the fact that it does not crash the game could make it count as a game feature.
The existence and revelation of this glitch led to rumors being spread about further secrets existing in Super Mario Bros. It is recognized as one of the greatest secrets and glitches in video game history, with the term "Minus World" coming to refer to areas in games that exist outside of normal parameters, such as in The Legend of Zelda. Frog Fractions designer Jim Stormdancer cited it as inspiration for making Frog Fractions the way he did, while Spelunky creator Derek Yu talked about his nostalgia for Minus World, lamenting a lack of mystique found in modern games. References to the Minus World can be found in both Super Paper Mario and Super Meat Boy.
Summary
The Minus World is accessed from World 1–2. In order to encounter it, players must exploit a glitch in order to maneuver Mario through the bricks separating the normal exit from the Warp Zone area. So long as players do not lock the screen in position, players can make Mario enter the first Warp Pipe before the "Welcome to Warp Zone!" text is revealed. The console did not have a method to check for collisions between tiles, and the task of checking all points around a tile for possible collision points was too difficult for the console's MOS Technology 6502. To compensate for this, the designers put boundary boxes around objects and compare a limited number of collision boundaries. Mario's sprite has two points, one on each foot, each detecting his collision with the floor. The game would normally eject Mario in the opposite direction he is going if he is considered inside a block, which can be averted by crouching while jumping into it and, at the exact right moment, pushing left, causing him to be ejected on the other side of the wall. The game then erroneously sets the far-left and far-right Warp Pipes to send him to World -1. When players successfully pull this off, they are presented with a screen reading World –1, and then Mario is put in a water level that loops the end with the beginning, and as a result, cannot be beaten. It is a copy of the stage, World 7–2, aside from the looping. Despite the appearance and the popular name "Minus World", it is not in fact a negative level number. Rather, the level is identified in the internal memory as "World 36–1", but when it displayed a blank tile is shown, as 36 is the tile number for a blank space. The reason the glitch occurs is because of a misread byte.
The Japanese version of the game on the Famicom Disk System has a different result from performing the glitch; instead of looping after Mario reaches the end of the level, it goes through three different levels until players reach the goal and the game ending. The Japanese levels start with an underwater level as well, with floating Princess Peach and Bowser sprites at multiple points. The reason why the two versions' Minus Worlds differ is due to the North American version using a cartridge and the Japanese version using a disk. Cartridges and disks arrange data in different ways, resulting in the different versions sending the offset the Warp Pipe receives arriving at a different byte in the programming.
History
When Super Mario Bros. creator Shigeru Miyamoto was asked about the Minus World, he denied authorship and said that it was not intended. When asked later about the Minus World, Miyamoto commented that while it was a glitch, the fact that it does not crash the game makes it a feature as well. Since its discovery, the Minus World has resulted in people believing that Super Mario Bros. designers hid secret levels for skilled players to find. It was featured in the third issue of Nintendo Power, describing it as "an endless water world from which no one has ever escaped." This appearance provided photographic evidence of the glitch.