From Bulbapedia, the community-driven Pokémon encyclopedia.
Glitch City (Japanese: 故障都市 Accidental City) is a term used by players of the Pokémon games to refer to corrupted maps that result from a glitch present in the Generation I games of Pokémon Red, Blue, and Yellow.
Accessing Glitch City
Players may activate the glitch that causes Glitch City to appear by following these steps:
- Travel to the Safari Zone. Enter a Safari Game, then walk around for 150 steps. Pokémon may be caught, and will not have any negative consequences from this glitch.
- In the Safari Zone, save the game, turn it off, then turn it back on.
- Exit the Safari Zone. The attendant will ask if the player would like to join a Safari Game. Answer "no".
- Fly anywhere (for the easiest Glitch City to walk in, go to Cinnabar Island's east coast).
- After taking 500 steps, the Safari Zone's PA will ring, and the player will be teleported into the Safari Zone gatehouse.
- Leave the gatehouse through the south exit, and the player will be in Glitch City.
Escaping Glitch City
The only way to fix the glitch is to Fly or Teleport out of Glitch City. There is no need to worry about any permanent corruption. However, if the player saves in Glitch City and does not have a Pokémon that can allow them to leave, they will need to replace their save file with a new and empty one to escape.
In the Pokémon games, doors and cave entrances are coded as "warps" that are placed on tiles. Warps have two values: one value specifies what map the player should be warped to, and the other specifies which warp on the map the player should be teleported to (warps can only lead to other warps).
This glitch occurs because the player manages to trick the game into letting him or her out of the Safari Zone while the step timer is still running, by saving the game. When the steps run out, they are warped to the Safari Zone gatehouse, regardless of whether or not they are actually in the Safari Zone.
The reason the player may find themselves in Glitch City upon exiting the gatehouse is because the door that would lead out to Fuchsia City is coded so that the warp points to warp 4 on the last map the player was on. This would work perfectly normally, however, many areas in Generation I Kanto lack a warp 4, and so the glitch goes through. Maps that do have a warp 4, such as Viridian City, do not result in a Glitch City, instead taking the player to wherever the warp is and letting them leave it normally.
Due to warp-breaking, of course, this means that Glitch City is nothing more than a corrupted version of whatever map the player was on when he or she ran out of time. When the Town Map is viewed in Glitch City, the map will say that the player is in the area they were in just before entering Glitch City, because they technically are in the area, just an extremely corrupted version of it. This is why the Glitch City found by running out on Route 17 will cause the player to constantly walk downward and why attempting to use the Bicycle results in the message "You can't get off here.", and why statues from Victory Road can be seen in its Glitch City.
The dimensions of the source map are apparently preserved: going too far in any direction while in a Glitch City will cause the player to walk outside of the map, thus crashing the game. The only crash-free Glitch City is that of Pallet Town, which does not allow the player to move at all. On a side note, Pokémon Stadium's Game Boy Tower mistakes such crashes for a corrupted game.
Although some aspects of the source map of Glitch City are preserved, such as tiles, most other attributes are completely changed, such as what is and isn't walkable terrain. There are essentially five types of tiles in Glitch City: Walkable tiles, ledges, walls, Surf tiles, and traps, which can be walked onto but not walked off of. Map links, which allow players to travel between two adjacent areas without a warp (such as from Route 22 to Viridian City), are also apparently ignored, so if a player manages to navigate to where an adjacent map should be and try to walk into it, the result will be the same as if they walked outside of the map.
In Pokémon Yellow, Glitch City has a profound effect on Pikachu's overworld AI, causing it to run to and from random places. Walking onto certain glitched tiles also make it disappear, though after the player leaves such tiles, Pikachu will reappear and follow the player's recorded path. Pikachu's happiness level will reset in Glitch City, causing it to dislike the player.
Specific Glitch Cities
Cinnabar Island Coast
In the Glitch City accessed through Cinnabar Island's east coast, players are sometimes able to Surf north until they reach the barrier that normally prevents them from leaving Route 20 to the north.
Because invisible walls exist on the western side of this Glitch City, traveling north is the easiest way to escape it. If the player goes to the westernmost checkerboard pattern of water in the area, goes left of it one step, then back right, and presses start, the entire area will become Surfable water.
Route 13 (Yellow)
In Pokémon Yellow, if a player goes to Route 13 to activate the glitch, after leaving the gatehouse the player will be transported to a Glitch City where any move the player makes will send them to the Saffron Gym. After leaving the Gym, the player end up in a completely different Glitch City.
Prevention in later games
The Safari Zone was not included in Pokémon Gold, Silver, and Crystal, though it cannot be stated with any certainty that its removal is a result of the Glitch City phenomenon. In any case, its inaccessibility prevents the glitch from occuring the same way it did in Pokémon Red, Pokémon Blue, and Pokémon Yellow. A similar effect, however, can occur after capturing or defeating the Glitch Pokémon ?????.
In Generation III and IV games, including the remakes of Generation I, the player cannot save within the Safari Zone (the menu option instead being replaced with "retire"), thus preventing players from tricking the game and disallowing the reappearance of Glitch City. However, using an Action Replay on the Sinnoh games to run/walk through walls, then biking through certain places will result in a corrupted version of a city, in which many tiles are white. When jumping off the bike, the character is a scrambled block.
- Pressing start while in Glitch City to bring up the menu often changes the appearance of the glitched terrain. This is sometimes permanent for the remainder of the time spent in Glitch City, and will at times change all of the tiles into Surf tiles.
- Wild Pokémon data is inherited from the map that the player entered Glitch City from. Tentacool, for example, are common in the Cinnabar Island Coast Glitch City. This does, of course, mean that Missingno. and 'M can be made to appear in Glitch City.
- Background music is also inherited from the map the player entered from. Sea-only routes play their background music, which is normally unheard due to Surf having its own background music.
- If the final step is taken as the player jumps a ledge in an area with a fourth warp, when returning to that area, the player may be able to walk through walls.
- Glitch Cities in Pokémon Yellow are different from those in Pokémon Red and Blue.
- Glitch City cannot be accessed if the player runs out of steps in Celadon City, Cerulean City, Lavender Town, Saffron City, Fuchsia City, Viridian City, Pewter City, or Vermilion City, as those maps all have fourth warps.
- Normally Cuttable trees cannot be cut down in Glitch City, no matter how many times the move is used on it. No signs are readable, doors cannot be entered, and cave entrances (such as the one found in the Cinnabar Island Coast Glitch City) will freeze the game if entered. This is because objects (such as the invisible ones placed over signs) and warps (such as those placed over doors and cave entrances) are ignored in Glitch City.
- If the last step made before causing the glitch was while the player was spinning (such as from the tiles in the Viridian Gym), the player will always be spinning while walking, even if this occurs in an area from which it is impossible to enter Glitch City, such as Viridian City.