12TB Steam Leak: Everything We Know About the Portal 2 Builds and Half-Life 3 Claims

The Steam2 Teraleak, as it's being called, reportedly contains around 12TB of data from Valve's old Steam infrastructure, including thousands of game depots covering content uploaded between 2003 and 2013.

And it's not limited to Valve games.

Researchers have reportedly found early builds, prototypes, unused assets, and development files connected to games including Portal 2, Left 4 Dead, Counter-Strike: Global Offensive, Spore, Dragon Age: Origins, Batman: Arkham Asylum, and others.

Some of the material comes from games that were eventually released. Some comes from projects that changed dramatically during development. And some appears to be connected to games that never saw the light of day.

That's what makes the leak so significant. This isn't just another dump of unreleased game content. If the reported origins of the archive are accurate, it is a snapshot of how a large part of the PC games industry worked during Steam's early years.

Here's what we know about the 12TB Steam leak, what's been found so far and what remains unclear.

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What is the 12TB Steam leak?

The archive reportedly contains data from Steam2, an older version of the infrastructure Valve used to distribute games through Steam. The files cover content uploaded between roughly 2003 and 2013 and are organised into thousands of “depots.”

These can contain different versions of games and other Steam content, including released builds, updates, beta versions, prototypes and development files. The important part is the age of the data.

We're not looking at Valve's current Steam infrastructure or a dump of its modern development servers. The material reportedly comes from an older system that was eventually replaced.

That explains why the archive contains such a strange mixture of games and projects. Valve's own titles are in there, but so are games from publishers that were using Steam during the same period.

In other words, this isn't just a Valve leak. It's potentially a much broader piece of early Steam history.

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Was Steam hacked?

The evidence available so far suggests no conventional hack took place.

Valve-focused content creator and dataminer Gabe Follower said he verified that the material was obtained through a publicly accessible endpoint associated with the old Steam infrastructure.

If that account is accurate, someone didn't break into Valve's modern systems and steal 12TB of data. Instead, the archive appears to have come from legacy infrastructure that was still accessible.

That's a very different scenario. It also leaves an important question unanswered: when was the data actually collected?

Ars Technica has reported that the archive may have been gathered recently from an accessible endpoint, although it's also possible that some or all of the material had been collected privately over a much longer period before appearing online.

So the origin of the data is becoming clearer, but its complete history isn't.

Why does the Steam leak stop at 2013?

The 2013 cutoff may be one of the biggest clues to the archive's origins. Valve began moving away from its older Steam2 infrastructure around this period as it transitioned to SteamPipe, a newer content-distribution system.