12TB of Valve's data from 2003-2013 has leaked online, and Episode 3 content isn't off the table yet

Published Aug 29, 2026, 5:49 PM EDT Simon is a Computer Science BSc graduate who has been writing about technology since 2014, and using Windows machines since 3.1. After working for an indie game studio and acting as the family's go-to technician for all computer issues, he found his passion for writing and decided to use his skill set to write about all things tech. Since beginning his writing career, he has written for many different publications such as WorldStart, Listverse, and MakeTechEasier. However, after finding his home at MakeUseOf in February 2019, he would eventually move on to its sister site, XDA, to bring the latest and greatest in Windows, Linux, and DIY electronics. Sign in to your XDA account Summary 12 TB of Valve data (2003-2013) leaked online, sparking fans to dig through builds. It includes beta builds and prototypes, such as Portal 2's early versions, F-Stop, L4D, and CS:GO assets. Fans are hoping for Half-Life 2: Episode 3 files inside the archive, but no relevant data have been found yet. Data leaks of games from the past, whether they were actually released or not, are always fascinating. For games that never made it out the gate, there's a cool element of "What if" where we picture a world where the game was never canned. For games that did release, it gives cool insight into how the developers fleshed out the game into the form we know today, and we may even see cut content that we wish never got dropped. Now, fans of Valve's games have seemingly hit a goldmine, as someone has reportedly leaked 12 TB of data spanning from 2003 to 2013. And while nobody has found any evidence of Half Life 2: Episode 3 content in it yet, there's a chance it may be hidden in there somewhere. 12 TB of Valve's game data has leaked online People are toiling over the data as we speak Over on X, user @GabeFollower reported that 12 TB of Valve's data between 2003 and 2013 has leaked online. It contains beta builds of Valve's games, including some early prototypes of Portal 2. This includes F-Stop, when Valve reportedly tried experimenting in the Portal universe with a camera-based mechanic before it scrapped the idea and went back to portals. It also means that there's a chance that early Half-Life2: Episode 3 builds are in there, but at the time of writing, nobody has found anything related to the legendary sequel that never came. There's 12 TB after all, so it's going to take a long time for the community to sift through all the data and work out what it all means.