Gun is a Revisionist Western-themed action-adventure video game developed by Neversoft and published by Activision for Microsoft Windows, PlayStation 2, Xbox, GameCube, and as a launch title for the Xbox 360 in 2005. The PlayStation Portable version was released a year later under the title Gun: Showdown, this version features new side-missions, a multiplayer mode, and other additions that were not available in the console versions.

Gun features an open world environment, including side-missions that add to the story. Players control the protagonist, Colton White, from a third-person perspective. While traveling from town to town, bandit attacks are frequent and players must either escape or defend themselves.

Players can hunt and kill various animals like buffalo, wild horses, and even stray dogs and farm animals. The player can also cause mayhem within communities, but can attract attention from lawmakers and other gunslingers by doing so. They act as gunslingers protecting righteousness or seek reputation as they face resistance fighters, local lawmen, renegade soldiers and vengeful Apaches and Blackfoot. A Town Patience meter goes down every time a civilian is killed. Once the patience meter reaches zero, a showdown ensues between the player and the locals.

Several minigames are included in Gun. As the player progresses through the game, they can choose to complete side missions, including poker tournaments, cattle herding, law enforcement and bounty hunting. Players can purchase upgrades using money obtained from these optional activities and by mining gold veins.