Left 4 Dead is a cooperative first-person shooter video game with survival horror elements, developed by Valve South and published by Valve Corporation.
 The game uses Valve's proprietary Source engine, and is available for Microsoft Windows, Xbox 360 and OS X.
 Development on the game was completed on November 13, 2008, and two versions were released digitally: A downloadable digital version, released on November 17, 2008, and a digital retail disc version, with a release date determined by region.
 The digital retail disc version was released in North America and Australia on November 18, 2008; and in Europe on November 21, 2008.
Garry's Mod (commonly abbreviated as GMod) is a sandbox physics game created by Garry Newman and developed by his company, Facepunch Studios.
 "Garry's Mod" was originally a mod for Valve Corporation's "Half-Life 2", but was later made into a standalone release in 2006 for Microsoft Windows, published by Valve Corporation.
 Later updates saw an OS X port, added in 2010, and a version for Linux in 2013.
Valve Corporation is an American video game developer and publisher founded in 1996 by Gabe Newell and Mike Harrington.
 The company is currently based in Bellevue, Washington.
 Valve's first game was "Half-Life", a first-person shooter released in 1998.
 It received universal acclaim and sold over 9 million units in retail.
 Alongside "Half-Life"' s launch, Valve released development tools to enable the player community to create content and mods.
 The company then proceeded to hire the creators of popular mods, such as "Counter-Strike", which became the most popular multiplayer first-person shooter for the next decade.
Kelly Bailey is a composer, musician, game designer, conceptual artist and programmer.
 He was the senior game designer of sound and music at Valve Corporation until he left in 2011 with Mike Dussault, to concentrate on their project Sunspark Labs LLC.
 Valve composer Mike Morasky mentioned in February 2014 that Bailey had returned to Valve but in a February 2016 article on Forbes it was reported he has founded his own company, IndiMo Labs, and he's no longer with Valve.
Source Filmmaker (abbreviated as SFM) is a video capture and editing application that works from inside the Source game engine.
 The tool, created by Valve Corporation, was used to create over 50 animated shorts for its Source games, including "Team Fortress 2", the "Left 4 Dead" series, and "Half-Life 2".
 On June 27, 2012, Valve released a free open beta version of the SFM to the gaming community via its Steam service.
Alien Swarm is a freeware multiplayer top-down shooter video game by Valve Corporation.
 It is a remake of the "Alien Swarm" mod for "Unreal Tournament 2004", and it was developed by the original team, who were hired by Valve Corporation during the course of the development process.
The Potato Sack is the name of an alternate reality game (ARG) created by the Valve Corporation and the developers of thirteen independent video games to promote the release of Valve's title, "Portal 2", in April 2011.
 Valve president Gabe Newell envisioned the game as a "Cross Game Design Event" in December 2010, and allowed the developers a free rein to design the game using Valve's "Portal" intellectual property.
 The game, requiring players to find and solve a number of puzzles hidden within updates of the thirteen games, ultimately led to the opportunity for players to release "Portal 2" about 10 hours earlier than its planned release by playing games under the pretense of powering up GLaDOS, the sentient computer antagonist from the "Portal" series.
 The ARG's theme of potatoes is based on plot elements within "Portal 2", specifically that for part of the game, GLaDOS's personality module is run off a potato battery.
In video games, skin gambling is the use of virtual goods, which are most commonly cosmetic elements such as "skins" which have no direct influence on gameplay, as virtual currency to bet on the outcome of professional matches or on other games of chance.
 It primarily has occurred within the player community for the game "" by Valve Corporation, but practice of it exists in other game communities.
 Valve also runs the Steam marketplace which can be interfaced by third-parties to enable trading, buying, and selling of skins from players' Steam inventories for real-world or digital currency, though Valve itself condemns the gambling practices and such activity violates Steam's Terms of Service.
Half-Life: Opposing Force is an expansion pack for Valve Software's science fiction first-person shooter video game "Half-Life".
 The game was developed by Gearbox Software and Valve Corporation and published by Sierra Entertainment on November 19, 1999.
 "Opposing Force" is the first expansion for "Half-Life" and was first announced in April 1999.
 Randy Pitchford, the lead designer on the game, later noted that he believed Gearbox was selected to develop "Opposing Force" because Valve wanted to concentrate on their future projects.
 Over the course of development, Gearbox brought in a variety of outside talent from other areas of the video games industry to help bolster various aspects of design.
Valve Corporation is an American video game developer and digital distribution company headquartered in Bellevue, Washington.
 The company is known for its software distribution platform Steam and the "Half-Life", "Counter-Strike", "Portal", "Day of Defeat", "Team Fortress", "Left 4 Dead", and "Dota 2" games.

Question: What is the name of the man that works at Valve Corporation who created GMod?
Answer: Garry Newman