Pokémon Red / Blue · Game Boy · 1996 · Map Corruption · Discovered by Community
A mishandled exit from the Safari Zone can drop the player into "Glitch City" — a scrambled, mostly impassable landscape assembled from corrupted map data. The bizarre, walk-through-walls dreamscape became one of the most recognisable glitches of the first Pokémon generation.
Pokémon Red and Blue track a hidden step counter while the player is inside the Safari Zone, ending the excursion when the steps run out. By starting the Safari Zone's expiry sequence and then leaving in an unintended way — exploiting how the game saves and restores the player's position — players could land in an area the game was never meant to assemble. The result, nicknamed Glitch City, is a corrupted map built from whatever data happened to be in memory: a patchwork of mismatched tiles, floating fragments of buildings, and large regions the player can walk through as though the walls were not there. Glitch City is usually a one-way trip. Much of it is impassable or leads nowhere, and many routes out simply loop back or freeze, so the safest escape is often to fly to a known town or reset. Its haphazard, half-real appearance made it a favourite subject of 1990s playground rumour and early internet documentation, sitting alongside MissingNo. as proof that the polished cartridge concealed a fragile structure that careful misuse could pull apart.
The Safari Zone uses a hidden counter to limit how long the player can explore. When that counter expires the game runs a sequence to remove the player from the zone and restore their previous location. By interfering with the timing of that sequence — beginning the exit while the game's record of the player's position is in an inconsistent state — the player can be placed at coordinates the game cannot map to a real, designed area.
Rather than refusing to load, the engine assembles a screen from whatever tile and object data is currently in memory. The outcome is non-deterministic in feel: the exact layout depends on what the game was holding when the corruption occurred, which is why no two descriptions of Glitch City look quite the same.
Because it produced a strange, explorable space that looked nothing like the real game, Glitch City spread quickly through schoolyard accounts and the earliest fan websites, often tangled together with exaggerated or invented consequences. Like the Mew-under-the-truck rumour and MissingNo., it became part of the oral tradition that grew up around the first Pokémon games.
Its lasting appeal is partly aesthetic: Glitch City offered a glimpse behind the curtain of a beloved, tidy world, replacing it with something fragmentary and uncanny. For many players it was a first encounter with the idea that a game is ultimately data, and that data can be coaxed into showing places no designer ever drew.