Interlopers has been online since 2004. It posts selected Steam game news but its focus is on content creation.

LanManiaX2 is a map and mod resource. But don’t let that simple description fool you, it contains a wealth of news and information.

Leak Free is a Source engine development community started in 2004, which consists of useful tutorials and a helpful community to answer all of your level design, modeling, and programming questions. One of the most noted features is the Valve Hammer Editor Error Listing, which describes all the errors in the software and how you [...]

Mod DB is the largest website dedicated to supporting independent development of games

Obsidian Conflict is a co-operative modification created for Half-Life 2. It is a community based mod with focus on fun, co-operative and physics-related puzzles. The mod has an open story, but is still set in the Half-Life 2 universe.

OzSource is the home of the Australian Gaming Combine. Steam discussion, Community Portal, Gaming news and opinions, critiques, retrospectives. Oz Source has been resurrected from its Half Life 2 Deathmatch origins.

Pájaros de Barro is a Spanish Gaming Community which offers public servers and support (tutorials, videos, forums, articles…) for Team Fortress 2 and Left 4 Dead as well as updated and fully spanish translated news and interviews related to Steam and Source Engine based games.

Phenomena On Break is a community brought together by their love of Valve games and games in general. They have used Valve games for over a year to make over one hundred comics based in the Half-Life universe, as well as the use the Source Engine and Gmod to create original universes and characters. They [...]

Planet Half-Life is the daddy of them all. It’s been online longer than most and is generally updated daily.

PlanetPhillip.com contains the most comprehensive database of single player maps and mods for the Half-Life series of game on the Internet.

Podcast 17 is a weekly verbal tour of the Half-Life community. It covers everything related to the Half-Life universe and features lively, informative recordings.