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 gotten 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