The archive appears to span a decade of Steam history, from lost Valve builds to third-party game prototypes.
A massive 12TB archive first reported for its collection of old Valve files now appears to stretch far beyond the company’s own games, with Steam depots tied to hundreds of titles and obtainable builds from third-party games including Grand Theft Auto 3 and Mafia 2.
Information about the so-called Steam "teraleak" began circulating over the weekend, initially drawing attention for material linked to Portal 2, Counter-Strike: Global Offensive, Left 4 Dead, and Half-Life 2: Episode 3. Further digging, however, suggests the archive covers a much broader slice of Steam’s early history, including material from numerous third-party developers and publishers.
What games are included in the 12TB Steam teraleak?
The archive contains Steam file groups known as depots, which group together files distributed through Steam. A list shared on Reddit by user RefreshingCapybara includes depot names associated with hundreds of games, alongside trailers, teasers, soundtracks, demos, game trials, and other material.
"Not to be hyperbolic but this may be one of if not the biggest leaks to occur due solely to the number of games it involves," RefreshingCapybara said.
The list itself does not confirm exactly what is contained within every depot. However, Ars Technica reported that game preservation website Hidden Palace has identified numerous depots containing obtainable builds. These include prototypes of Spec Ops: The Line, Sid Meier’s Civilization V, Mafia 2, and Grand Theft Auto 3.
There is plenty on the Valve side as well. Dataminers have reportedly uncovered the complete 2009 Portal 2 beta, alongside prototypes for Left 4 Dead and Counter-Strike: Global Offensive, as well as files from Valve’s cancelled puzzle game F-STOP. The Portal 2 beta differs considerably from the version eventually released in 2011. It still takes place inside the ruined Aperture Science facility, but uses pre-recorded messages from GLaDOS to guide the player through its early test chambers rather than Wheatley, while other personality cores also play a larger role.
YouTuber Gabe Follower has also reported finding the Weaponizer, an unfinished weapon previously linked to Half-Life 2: Episode 3. Information about the Weaponizer had previously appeared in a 2011 leak inside a directory labelled "ep3", while a similar-looking weapon was later shown in footage of the cancelled Episode 3 included in Valve’s Half-Life 2 20th anniversary documentary.
The amount of third-party material also makes the archive more complicated than a collection of old Valve builds. Tyler McVicker said on social media, "That archive contains a significant amount of third-party content, meaning we are dealing with a dramatically more dangerous situation than if it were just some Valve builds."
Where did the 12TB Steam teraleak come from?
The files are tied to Steam’s older Steam2 content system and cover material dating from between 2003 and 2013. Gabe Follower said the material was obtainable through a publicly accessible Steam2 endpoint, while the Reddit post cataloguing the depots similarly claims that an unprotected Steam endpoint allowed the files to be accessed.
What remains unclear is when the files were obtained and how the full 12TB collection came together. According to a report by Ars Technica, the archive may include builds obtained from different sources over time before eventually being assembled into the larger collection.
Many pre-2013 Steam builds had previously been considered lost media by preservationists and collectors, adding to the possibility that some of the material had been kept privately for years. One clue pointing in that direction is a README file included in the archive, which contains the line, "warm n good wishes to all hoarders who had stuff from this collection".
Valve has not publicly commented on the archive. And with 12TB of files still being sifted through, more games, prototypes, and previously unseen material could still surface as the archive is catalogued.
