Sandbox physics game created by Garry Newman and developed by Facepunch Studios on PC.
The game was originally a mod for Valve Corporation's Half-Life 2, but was made a standalone game in 2006 for Windows. An OS X version was released in 2010, and a Linux version was released in 2013.
The game has no set objective and instead gives the player the freedom to make his/her own maps, add ragdolls to the map, and manipulate the ragdolls.
Due to its freedom, players or developers are able to make custom game modes for Garry's Mod, such as Trouble in Terrorist Town and Murder. Content creators can also use its freedom to make videos through stop motion of ragdolls and props posing for frames and rendering them into a GMod video.
Garry's Mod runs on the Source engine made by Valve, along with other games like Team Fortress 2 and Counter Strike: Source. As a result, many mods for Garry's Mod borrow assets from those games.