From Bulbapedia, the community-driven Pokémon encyclopedia.
Glitch City is a term used by Pokémon gamers to refer to a hidden fictional city caused by a bug that occurs in the Pokémon video game Red, Blue and Yellow versions. The term Glitch City is not to be confused with Blue Hell - a more general term that refers to a non-existent area in any interactive game.
Finding Glitch City
- Go to the Safari Zone and walk around about 150 steps. (this will prevent having to walk/Surf up and down continuously later)
- When asked "Leaving early?" say No.
- In the Safari Zone, save the game, turn it off and turn it back on again.
- The man will ask if you want to join a Safari Game. Say no.
- Fly anywhere (for the Glitch City that is easiest to walk around in, fly to Cinnabar Island's east coast)
- Move for 500 steps, and then "Ding-dong!" will appear
- Leave the Safari Building and you will be in Glitch City
In the Pokemon games, doors, cave entrances, etc., are coded as "warps" that are placed on tiles. Warps have two values: a value that specifies which map to take the player, and a value that specifies which warp on that map to take the player (Warps can only lead to other warps).
This glitch is caused by the player managing to exit the Safari Zone with the timer still running. The timer counts their steps, and when they run out of time, they are taken back to the Safari Zone gatehouse, regardless of whether or not they are actually in the Safari Zone. Now, the reason the player finds themself in Glitch City upon exiting the gatehouse is that the warp on the door that would lead to Fuschia City actually points to Warp 4 on the last map you visited (hex:FF), which would work fine except that many maps don't have a Warp 4. This is why Glitch City works on some maps and not on others -- maps like the Cinnibar Coast and Cycling Road will result in Glitch Cities because they don't have a Warp 4, but maps like Viridian City and Fuschia City won't result in Glitch Cities because they do have a Warp 4.
Consequently, Glitch City is really nothing more than a corrupted version of whatever map you were on when you ran out of time. When a player views the Town Map while in Glitch City, the map will say that they are in the area they were in prior to entering Glitch City, because technically, they are in that area -- they're just in an incredibly corrupted version of that area. This is why, in the Cycling Road Glitch City, the player will constantly be walking downward (and why, when they try to ride the bike, they get the message "You can't get off here."). It is also why, in the Victory Road Glitch City, statues from Victory Road can be seen.
The dimensions of the "source map" are apparently preserved -- going too far in any direction while in a Glitch City will cause you to walk (or SURF) outside the map, crashing the game. Oddly, Pokemon Stadium's GBA Tower mistakes this crash for a corrupted game.
Although some aspects of the "sources" of Glitch City are preserved (such as Cycling Road's slope and Victory Road's statues), most other attributes of the source maps are completely changed, such as what is and what isn't walkable terrain. There are essentially five types of tiles in Glitch City: walkable tiles, ledges, walls, SURFable tiles, and traps -- traps being tiles that, once you walk on them, you can't get off them. In many Glitch Cities the player cannot move at all. Because of the terrain alteration, there are many cases where you can SURF outside the map (see previous paragraph).
Apparently, in Glitch City, map links are ignored. That is, maps are "linked together" such that you can walk from one map into another (for example, from Pallet Town into Route 1); these links are ignored in Glitch City so that if you manage to navigate to where an adjacent map should be and try to walk into it, the results will be the same as if you walked outside of the map.
In Pokemon Yellow, Glitch City appears to have a profound effect on Pikachu's overworld AI, causing it to run to and from random places. Certain glitched tiles also make it disappear, although it will reappear and follow your "recorded" path once you leave the tiles.
The only way to end the glitch is to FLY out of Glitch City. Don't worry about the map being permanently destroyed -- the corruption is only temporary and you can safely return to the map that you entered Glitch City from at any time. However, saving while in Glitch City is not recommended, especially if you don't have a Pokemon that knows FLY in your party.
- Pressing START while in Glitch City (or fishing) often changes the appearance of glitched terrain. In some cases all terrain may be changed into SURFable water tiles.
- Wild Pokemon data appears to be "inherited" from the map you entered Glitch City from; Tentacool, for example, are common in the Cinnibar Coast Glitch City. However, the Cinnibar Coast Glitch City sometimes also contains MISSINGNO. and 'M for the same reason.
- The background music is also taken from the map you entered Glitch City from. The reason the overworld music plays on sea routes is because that IS the background music for the route -- you just never hear it because there's no land on that route and SURF has its own music.
- If the glitch is done whilst in the middle of jumping off a ledge in a route that has a Door 4, upon returning to that route, you may be able to walk through walls.
- The Glitch Cities found in the Yellow version are different to those that are found in the Red and Blue versions.
Cinnibar Coast Glitch City
In the Glitch City accessed through the Cinnabar Coast, in some cases players are able to surf in a northern direction until they reach the barrier that normally prevents them to leave Sea Route 20 northward. However, if a player surfs too far north (or in any direction), they will actually surf outside the map and crash the game.
Because invisible walls that trap the player exist on the western side of the city, going north is usually the only way to escape the "normal" Glitch City. If a player goes to the westernmost "checker-board" water pattern in the city, and goes left of it one square and then right one square, this will enable the entire city to become water (when the player presses "start") and allow the player to swim north until they surf outside the map. Once the player is far north, but not so far that they crash the game, the player can swim east or west for a long period of time until they exit the map and crash the game.
Other Glitch Cities
In the Yellow version, if the player goes to Route 13 while doing the Glitch City trick, the player will be transported to a Glitch City where any move the player makes will send him or her to the Saffron City gym. Once he or she leaves the gym, the player will be in a completely different Glitch City.
Prevention of Glitch City in later games
The Safari Zone was not included in the Gold, Silver and Crystal versions -- regardless of whether or not it was deliberately removed because of Glitch City (which has lead to much speculation but nothing is known for sure), the removal of the Safari Zone nonetheless prevents Glitch City from occurring the way it does in the Red, Blue and Yellow versions. However, there is a method of getting to a glitched area that is very similar in appearance to Glitch City. The player must use a GameShark to encounter a ?????. When it is defeated or captured, the player will be in the "GSC Glitch City".
In Pokémon Ruby, Sapphire, and Emerald, the player must exit the Safari Zone by using the Start menu and selecting "Retire." A warden also goes outside and blocks the door, so the player cannot return to the Safari Zone lobby while using the Safari Zone.
In Pokémon FireRed and LeafGreen, the player cannot save the game in the Safari Zone, therefore making it impossible to access Glitch City.
A way to reach the closest thing there is to Glitch City in Pokémon Gold and Silver without using the GameShark is to listen to the cry of any Machop (including the Pokédex and the ones in Goldenrod Mart) then immediately use the coin case. It is also possible to use this trick with another Pokémon to make the coin case say Coins: Which move? instead of Coins: (number of coins). Once a player activates this glitch, the game will automatically "reset" and the opening sequence will be glitched up and the colors inverted at certain points. Once the player begins gameplay, the buildings are all blue and red, the ground is multi-colored, and the battle screen colors are different. The game will also be much slower than usual.