Make use of several new puzzle-solving tools as you journey through over thirty test chambers, featuring a wide variety of obstacles Built on the Source engine. Requires that you own Portal 2 to play

Having survived a helicopter crash, you - a lone rebel - must make a desperate escape, as the Combine swarm the woods around you Built on the Source engine. Requires that you own Half-Life 2 to play

Set between Portal 1&2, you and a new friend will be tasked with repairing Aperture Science Built on the Portal 2 Community Edition branch of the Source engine. Requires that you own Portal 2 to play

In this upcoming horror shooter, you’ll have to fight your way through a 1990s Australia that’s descended into nightmare. Beware the huntsman spiders… they’ve ♥♥♥♥♥♥ bigger Built on the Source engine

Join the resistance, and fight back against the Combine’s control of Central Asia - several years before the events of HL2 Built on Source engine. Requires that you own Half-Life 2 to play

A short and polished mod from accomplished game designer and Source engine specialist Chuck Wilson Built on the Source engine. Requires that you own Half-Life 2: Episode Two to play

Play as either the U.S. Army or the Vietcong, in this fast-paced multiplayer shooter. Co-op and single-player modes are planned for full release. The Rhodesian Bush War setting is also slated as DLC

The first HL2 mod, and the first Source engine sandbox - predating even GMod. First released in 2004, it’s finally arrived on Steam (now built on Source SDK Base 2013)

A multiplayer celebration and loving parody of almost every notable game and mod built on Source & Goldsrc. Packed with modes, maps, weapons, and characters from across those engines’ histories

Thinking with Portals - now with ray traced lighting, some new textures, and a few surprises