Garry's Mod (unofficially abbreiviated as Gmod), was first released in November 26, 2006, and is a non-linear physics game, or as some would call it, a physics sandbox. There are no preset objectives for the game; it is only limited by the user's creative ability. Although Garry's Mod is a standalone game today, it requires the use of at least one game using Source's physics engine, ex. Left 4 Dead, Half-Life 2, or Team Fortress 2 (see: List of games supported by Garry's Mod).