Garrysmod

Garry's Mod (officially abbreviated as GMod) is a sandbox physics game using the Source engine. Garry's Mod has been available on Valve's content delivery service, Steam, since November 29, 2006.[2] Despite being a standalone game, Garry's Mod requires the user to own at least one game on Steam based on the Source engine, such as Half-Life 2, Counter-Strike: Source, Portal, or Team Fortress 2.[2] It is also commonly used for the creation and publishing of videos[4] [5] on YouTube, mainly from Team Fortress 2, Half-Life 2, Portal, Left 4 Dead andLeft 4 Dead 2. Garry's Mod was originally a modification for Valve's Half-Life 2, but was later made into a Steam game that was officially released on November 29, 2006.

Gameplay
Although Garry's Mod is usually considered to be a full game, it has no game objective and players can use the game's set of tools for any purpose. Garry's Mod allows players to manipulate "props" – various objects that players can place in-game. Props can be selected from any installed Source engine game or from a community created collection. The game features two "guns" – Physics Gun and Tool Gun for manipulating objects. The Physics Gun allows objects to be picked up, adjusted and frozen in place. The Tool Gun is a multi-purpose tool for performing various tasks, such as combining props, attaching them via ropes, and creating controllable winches and wheels. The Tool Gun is also used to control add-ons created by the community.

Another popular Garry's Mod concept is ragdoll posing. The player can create a ragdoll model from a Source game and pose it using a variety of tools.[6] This is a popular tool for making fan-made videos.

Garry's Mod takes advantage of the Source engine's modified version of the Havok Physics Engine,[7] which allows players to build contraptions that follow the laws of physics.

Credits
Garry's Mod Wikipedia: http://en.wikipedia.org/wiki/Garry's_mod

Official Garry's Mod Wiki: http://wiki.garrysmod.com/page/Main_Page

Garry's Mod Wikia: http://gmod.wikia.com/wiki/Garry%27s_Mod_Wiki

All information, references, and citation are on these Wiki's.