Valve 12TB leak reveals Portal 2, L4D betas

A massive 12TB archive of old Valve development files from 2003-2013 has leaked online, containing early builds of Portal 2 and Left 4 Dead.

A 12TB archive of old Valve development files, dated between 2003 and 2013, has leaked online. The leak was first flagged on Friday, August 29, 2026, by Twitter/X user Gabe Follower.

Gabe Follower stated the archive includes early versions of Portal 2, Left 4 Dead, and Counter-Strike: Global Offensive. It also contains assets from the cancelled Portal prequel known as F-Stop and potentially material related to the long-cancelled Half-Life 2: Episode Three.

Early Builds and Assets

So far, the community has identified a 2009-era Portal 2 beta build within the leak. This build includes a model for the "Weaponizer," a weapon previously associated with Episode Three that appears repurposed as a placeholder asset in Portal 2.

A fully playable Left 4 Dead beta build from June 2008 has also been found. This build features an early heads-up display, a work-in-progress lobby screen, and cut audio. The cut audio includes lines originally recorded for the character Zoey by Alésia Glidewell before Jen Taylor replaced her for the final game.

Source and Scope

The leaked material reportedly originates from Valve's old Steam2 content-delivery infrastructure. Valve phased out this system in favor of SteamPipe in the early 2010s. This leak is separate from a cyber attack on Valve's European shipping partner, CEVA Logistics, disclosed earlier in August 2026, which exposed hardware customers' personal data.

Valve has not commented on this latest archive leak.

With 12 terabytes of data to sift through, a complete picture of the archive's contents will likely take days to emerge. The community continues to research the files for any trace of Episode Three.

This leak follows a 2024 report from a trustworthy source detailing a new Half-Life project, codenamed HLX. That report, which cited datamined assets and a leak from a likely involved actor, stated the project was not just in development but was "playable, end-to-end." What is known for sure is that a Half-Life 3 project was in development around 2013/2014. That game was set to be a procedurally-generated, replayable title fusing Left 4 Dead-inspired gameplay with scripted story moments.

It was cancelled because it was built on the unfinished Source 2 engine.

Source: Eurogamer