A method of cheating in PC-based multiplayer first-person shooters, Wallhacking allows players to see through (and in some cases shoot through) level geometry. This conduct is obviously frowned upon, and people caught using wallhacks are usually permanently banned from servers upon their detection. Wallhacks are often achieved by modifying the game's code through an external source, such as video drivers, a separate executable that runs in parallel with the game, and modified game patches.
Wallhacking and general cheating in PC multiplayer games became so chronic, it eventually warranted the creation of anti-cheating software designed to detect if players were running modified code. The most popular cheat-detection software, PunkBuster, has been officially licensed by several prominent developers, and has proven an effective tool in preventing cheaters from overwhelming legitimate players.
In Shadowrun, for Games for Windows and Xbox 360, FASA Studios programmed a game mechanic called Enhanced Vision, which they referred to as "a balanced wallhack" in early interviews. In the game, the Enhanced Vision allows players to see color-coded icons through walls that represent other players in the match, as well as distance values indicating how far away they are. To balance this "wallhack," FASA limited the intrinsic maximum distance it reached, and alerted players detected by it though a short controller feedback and a visual cue. Any players who also have Enhanced vision will see the player activating it on their screen in a similar fashion, and any players who currently have Smoke mapped to their person are effectively invisible to Enhanced Vision at all but extremely close ranges, giving them a distinct advantage against players using it.