12TB Valve Leak Reveals Unreleased Portal 2, CS:GO Builds

A massive archive of internal Valve development files, estimated at 12 terabytes, has surfaced online, revealing a decade of unreleased game builds and assets from the company's legacy Steam2 content delivery system. The leak, which includes early versions of Portal 2, Left 4 Dead, and Counter-Strike: Global Offensive, along with materials potentially related to the long-canceled Half-Life 2: Episode Three, is being described as one of the largest in video game history. The archive was first flagged on August 29, 2026, by Valve dataminer Gabe Follower.