A type of hack used in computer games such as Counter-Strike to exploit the terrain of the arena. Wallhacks come in many forms, but they all are pieces of programming designed to give an unfair advantage to the user, usually a teenage script kiddie. Among known varieties of wallhack are "Ghostmode" (the ability to walk through walls), "Railgunning" (the ability to shoot through walls), "Glassworld" (the ability to see through walls), and many more. Because of the nature of online gaming, it is highly likely that wallhacks will continue to flourish, as for each one found and destroyed, another variation is created.

A cheat for FPS games (most often seen in Counter Strike that makes walls and solid objects more or less transparent, so it is possible to obtain knowledge of the whereabouts of other players.
Used by thirteen year olds and people who are unable to do good in a game without unfair advantages

To shoot someone through a wall without being able to see them