Aninvisible wall is a video game term for a boundary that limits where a player can go in a certain area, but doesn't appear in-game as any kind of visible obstacle, or as an obstacle that in reality could easily be bypassed, such as a mid-sized rock or short fence. In 2D games, the edge of the screen itself can form an "invisible wall", in that a character in play may be prevented from travelling off the edge of the screen. In 3D games, invisible walls are used similarly to prevent a player leaving the game-play area. This is often done in preference to using a more visible boundary, as this can reduce the realism of the environment.
In some games, errors in the programming, or use of computer game cheats can result in the wall becoming penetrable. If a user passes through the wall, they may enter an area of the game not intended for their use, for example an area containing unused items or portions of a level; or the user may find themselves reappearing on the opposite side of the game-play area. Alternatively, a run-time error could occur.