MissingNo and the Most Famous Game Boy Glitches
Updated: 5 hours ago
Every classic machine has its ghost stories, and the Game Boy's most famous one has a name, or almost a name. It is called MissingNo, short for missing number, and for a whole generation of players it turned a quiet afternoon of Pokemon into something between a magic trick and a haunting. It is probably the most famous software bug in video game history, and it lived on a grey plastic cartridge.
The Pokemon that was never meant to exist
MissingNo appears only in the first generation of Pokemon, the 1996 Red and Blue games (and their Japanese Red and Green originals) that ran on the original Game Boy. It is not a real, designed creature. It is what the game shows when it is asked to display a Pokemon that does not exist, a leftover slot in the data with no proper name, no artwork and no stats. On screen it usually turns up as a jagged tower of scrambled black-and-white pixels, and its Pokedex number and details are nonsense. Encounter it in the tall grass of memory and the game simply improvises a monster out of whatever data happens to be lying around.
MissingNo - Pokemon Blue MissingNo - Pokemon Red MissingNo - Pokemon Green
How players summoned it
The recipe spread across school playgrounds faster than any official strategy guide. First you visit the old man in Viridian City who offers to demonstrate how to catch a Pokemon. His little tutorial quietly stores your character's name in a corner of the Game Boy's memory. Then you fly straight to Cinnabar Island and surf up and down the narrow strip of sea along its eastern edge. That coastline has no wild encounters of its own, so the game reaches for that leftover name data instead and reads it as a list of Pokemon to throw at you. Out of that misread memory swims MissingNo, along with its cousin known as M with an apostrophe.
The trick that made it legendary
MissingNo would be a mere curiosity if it were not for one glorious side effect. Whatever item sits in the sixth slot of your bag has its quantity jump by 128 the moment you meet the glitch. Suddenly you have a mountain of whatever you were carrying. Players quickly learned to park their rarest, most precious items in that sixth slot, and so the glitch became the fastest known way to stockpile Rare Candies, which level a Pokemon instantly, and even Master Balls, which catch anything without fail. A bug in the code became, in effect, an infinite-item cheat that no cheat device was required to use.
Why it happens
None of this is magic, and that is the lovely part. The Game Boy has very little memory, so Pokemon reuses the same small patches of it for different jobs. Your name and the wild-encounter table happen to share space. On a normal route the encounter table is filled in properly, but the Cinnabar coast was never given one, so the game just reads whatever was left in that memory, which is the data from the old man's naming routine. Because the resulting Pokemon number points to an empty slot, the console draws its sprite from unrelated bytes and produces that famous wall of static. The bug is simply the Game Boy doing exactly what it was told, using the wrong page of its notebook.
A word of warning
MissingNo is mostly harmless, but not entirely. Meeting it commonly scrambles the graphics of your Hall of Fame records and can leave odd visual glitches until you reset, and in rarer cases players reported more serious corruption of their save. Nintendo was asked about it often enough that the official line became a simple do not do this, it may damage your game. The safest way to enjoy MissingNo today is exactly the way we do at the museum: as a story about how the hardware thinks, rather than something to try on a beloved original cartridge whose save you would hate to lose.
MissingNo was not alone
The first Pokemon games were a glitch-hunter's paradise, and MissingNo was only the most famous resident. The so-called Mew glitch let determined players meet the secret 151st Pokemon inside an ordinary cartridge, with no event and no cheat cartridge, by carefully juggling a trainer battle and the menu so the game miscounted who it was fighting. Others chased glitch cities, endless item tricks and stranger creatures still, trading rumours like ghost stories. Together they turned a children's monster-catching game into a decade-long puzzle about the machine underneath.
That is really why MissingNo endures. It is a reminder that these cartridges are not sealed boxes of magic but small, knowable computers, quirks and all, and that some of the Game Boy's best-loved moments were never designed by anyone. To explore more of the machine behind the myths, and the games that made it famous, come and wander the rest of the Game Boy Museum.
This piece is part of Pokemon and the Game Boy, the museum's guide to the whole Pokemon corner.
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