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 [...]

Map-Factory is a database hosting custom maps for any FPS. If you’ve make a map or simply came across a good map, feel free to submit it! If not, then just navigate through the site and you’ll find a lot of good maps!

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

My Aperture Labs: Welcome to the Aperture Science Enrichment Center’s Online Community Networking Web Service (or ASECOCNWS for short). Here at the ASECOCNWS, test subjects may attempt to solve Portal puzzles, build their own Portal puzzle environments, or simply talk about cake.

Netday is dedicated to custom maps of high quality only. Maps are added regularly (at least one per week). It also covers mods like Dystopia, Portal Prelude and JailBreak. The map reviews are both in English and in French. It is advert free and features direct download to all files.

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.

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.

Play Stuff is a Social, Creative Lounge, for Geeks and Gamers.

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.

Portal: Prelude, as its name states, is an unofficial prequel to the game Portal. Its story revolves around the pre-GlaDOS epoch, even before she was plugged in.