Out of bounds
Out of bounds refers to going beyond the normal boundaries of an area.
In Generation I
Going out of bounds is possible with a walk through walls glitch or cheat, the dokokashira door glitch via tile corruption, or arbitrary code execution.
In Generation I, every map has a boundary for each connection. These include x position (memory address D362 or D361 in Yellow) boundaries that are one tile wide and infinitely tall, and y position (memory address D361 or D360 in Yellow) boundaries that are one tile tall and infinitely wide. The y position increases for more southerly values, unlike other conventions.
Note that these x and y positions are not absolute for the whole game world. Rather, they are specific to an individual map, and when the player enters a new map connection or warp they will be updated.
If there is no valid connection and the game tries to load it, the game will place the player in map 255 (hex:FF) when they step on a boundary (known as a 'freeze tile'), and a freeze may happen (or Glitch Hell on emulators running Japanese Red, Green and v1.0 of Yellow).
It is possible to appear past the boundary if the player's x position or y position is one tile greater than (for east connections and south connections) or one tile less than (for west connections and north connections) the freeze tile.
This is possible through the looping map glitch trick (requiring a walk through walls glitch or cheat), arbitrary code execution or through a Glitch City, because Glitch Cities can put the player in a place with invalid coordinates.
If the player goes beyond an x boundary, the map will loop until x equals the west or east boundary after which the connection will be loaded, and if it was invalid a freeze or Glitch Hell (Japanese Red/Green/Yellow running on emulators) will occur. The 'copies' of the maps are called phantom towns, as warps and signs do not work there, and people cannot be found there.
If the player goes beyond a y boundary, they will encounter a Glitch City for a very high (very southerly) y position, and the same effects described above will happen for entering a north or south boundary.
If the boundary was invalid, the game will freeze (or Glitch Hell may appear in Japanese Pokémon Red, Green and Yellow running on emulators). If the boundary was valid, the relevant location will be loaded (e.g. FF in Route 3 loads Pewter City) and the coordinates will be updated.
Glitch Hell
Glitch Hell (video) is a term for the effects of stepping out of bounds in Japanese Pokémon Red, Green and Yellow (v1.0 for Yellow) on emulators, where the screen doesn't turn white and map corruption occurs, including corruption of the player's sprite in Red/Green. Glitchy sounds may play there.
Glitch Hell has not been observed on a real Game Boy running later revisions of Red, Green and Yellow, so it is probably an emulation error. (behavior on the initial revisions is unconfirmed)
Stepping out of bounds can easily be achieved by the tile corruption effect caused by the dokokashira door glitch if in Pallet Town the player steps near the 6th/7th posts from the bottom right and walks around until they can step through them.
In Japanese Yellow, since select glitches do not work, using a Rival's effect glitch item is probably the easiest method.
In Generation II
Going out of bounds may cause a number of effects that is influenced by the spot and location that the player went out of bounds from, including:
- A Glitch Dimension.
- A freeze.
- Actually taking the player to a new location without a freeze.
- A different effect, including a message box popping up.
In Pokémon Gold and Silver, if the player is taken to a new location their name may be corrupted. The Route 27 tune commonly plays in these glitch locations.
In Pokémon Crystal, instead of the player's name being corrupted, data for their party Pokémon like their names and OT, the player's number of badges, their money and items from all pockets as well as PC items may be changed. This includes the number of items in the pocket/storage system values.
The 'This Game Pak is designed only for use on the Game Boy Color.' message will appear in Pokémon Crystal if stepping out of bounds caused a Glitch Dimension, due to the register 'a' no longer being hex:11 (more information is available on the Glitch Dimension article).
In Generation IV
In Generation IV, the player can step out of bounds using the Tweaking or Elite Four door glitch (the Elite Four door glitch only works in Japanese Diamond/Pearl). Going out of bounds is also known as entering the void.
Unlike Generation I, coordinates in Generation IV are global instead of map specific[citation needed], so it is possible to get to many maps even including outdoor maps from indoors. There are invalid maps surrounding the space between existing maps known as Mystery Zones (Japanese HeartGold/SoulSilver: "----").
Walk through walls GameShark codes
These are GameShark codes that allow the player to walk out of bounds. All of them are for English versions, but the Generation I walk through walls code works for the Japanese versions too.
Generation I core series:
- 010138CD
Pokémon Gold and Silver:
- 0108A3CE
- 0108A4CE
- 0108A5CE
- 0108A6CE
Pokémon Crystal (thanks Xwingcmdr):
- 0100FAC2
- 0100FBC2
- 0100FCC2
- 0100FDC2