Plot: Half-Life 2: Deathmatch is a multiplayer first-person shooter video game developed by Valve. Released on Steam on November 30, 2004, it uses many of the assets from Half-Life 2 and its Source engine. It features new levels, optimized for multiplayer arena play, and a few new weapons. Wikipedia
Plot: Fortress Forever is a multiplayer first-person shooter total conversion modification for Half-Life 2. The game is based on Team Fortress Classic, and has been created by the Fortress Forever development team. Wikipedia
Plot: Minerva is an episodic series of single-player modifications for Valve's Half-Life 2. The mod was created by Adam Foster. Installments are released as each is finalized: the three releases for the Metastasis chapter have already been made, with the third installment released on October 1, 2007. Wikipedia...
Plot: Deathmatch Classic, also simply known as DMC, is a multiplayer mod for Half-Life. It was released as a free download with the 1.1.0.7 patch of the game on June 1, 2001, but is now charged for on the Steam store.
Plot: Aperture Tag: The Paint Gun Testing Initiative is a 2014 first-person puzzle-platform video game developed by the Aperture Tag Team. Originally made as a mod of Valve's Portal series, it was released on July 15, 2014. Wikipedia
Plot: Counter-Strike: Condition Zero is a first-person shooter video game developed by Ritual Entertainment, Turtle Rock Studios, and Valve, and published by Sierra Entertainment and Valve. The follow-up to Counter-Strike, it was released in March 2004 for Windows. Wikipedia
Plot: Minerva is an episodic series of single-player modifications for Valve's Half-Life 2. The mod was created by Adam Foster. Installments are released as each is finalized: the three releases for the Metastasis chapter have already been made, with the third installment released on October 1, 2007. Wikipedia...
Plot: Half-Life 2: Lost Coast is an additional level for the 2004 first-person shooter video game Half-Life 2. Developed by Valve, it was released on October 27, 2005, through the Steam content delivery service as a free download to owners of the Windows version of Half-Life 2. Wikipedia