Massive 12TB Steam Leak Reveals Lost Portal 2 and Half-Life Development Files

A massive 12TB Steam archive leak has exposed years of old game development data, including unreleased builds, beta content, unused assets and prototypes dating from roughly 2003 to 2013.

The archive is reportedly connected to Valve's old Steam2 infrastructure and contains material from both Valve games and third party titles. Researchers are still going through the files, so the full list of discoveries is not known yet.

Among the biggest findings so far are early versions of Portal 2, Left 4 Dead and Counter-Strike: Global Offensive, along with material from the cancelled F-Stop project and assets connected to Half-Life 2: Episode 3.

Half-Life 2: Episode 3 Weaponizer discovered

The Half-Life discovery getting the most attention is a 3D model for the Weaponizer, a concept weapon previously associated with the cancelled Half-Life 2: Episode 3.

The Weaponizer was designed around the idea of turning objects into ammunition. The model had previously been shown in connection with Valve's Episode 3 development, but its appearance inside an early Portal 2 build gives researchers another piece of evidence about how Valve reused assets during development.

However, there is an important distinction.

The leak has not produced a confirmed complete or playable Half-Life 2: Episode 3 build. Current evidence points to individual Episode 3 related assets and files rather than a finished version of the cancelled game. Ars Technica also reported that no playable Episode 3 depot has been verified so far. 0

Portal 2 beta is one of the biggest discoveries

The archive appears to contain an early Portal 2 build from July 2009, giving players a look at the game before Valve moved toward the version eventually released in 2011.

Modders and preservation researchers have reportedly reconstructed parts of the build so it can be played and examined.

• The build comes from Portal 2's early Core Hub development period.
• GLaDOS has different dialogue and animations.
• Her role is more passive compared with the final game.
• Some unfinished scenes use placeholder assets from other Valve games.
• Early gameplay concepts that were later removed can be seen in the files.
• The build contains a model of the Weaponizer.

Other unused Portal 2 material includes concepts involving adhesive gel, slow motion mechanics and different portal designs. Cut dialogue and alternative sequences are also being examined by researchers. 1

F-Stop gives Portal fans another look at Valve's plans

The leak also contains early material from F-Stop, a cancelled Portal universe project that was being developed before Portal 2 took its final form.

Instead of relying on the portal gun in the same way as Portal, F-Stop was built around a camera based gameplay mechanic. The newly discovered material provides additional evidence of how different Valve's plans for the Portal series were during this period.

Early Left 4 Dead build has also surfaced

An early Left 4 Dead build from June 2008 has reportedly been recovered from the archive.

The version is noticeably different from the final game and contains several development leftovers.

• Different HUD elements
• Different voice lines
• Altered map sections
• Unfinished assets
• Early development material reused from other Valve projects

These files offer a look at how Left 4 Dead changed before its final release.

CS:GO looked very different during development

The archive also contains early Counter-Strike: Global Offensive material.

The early version reportedly looked much closer to Counter-Strike: Source, with a different user interface and early versions of maps.

Researchers have also found several unused or early gameplay elements, including an MP5-Active weapon, early knife models, cut grenade mechanics and a Riot Shield concept linked to Counter-Strike 1.6.

The leak includes games beyond Valve

This is not simply a Valve archive.

Reports indicate that the massive collection also contains development material from third party games released through Steam during the same period.

Early material from games connected to Call of Duty, Resident Evil, Mirror's Edge, Batman: Arkham Asylum and Dragon Age: Origins has reportedly been identified. More discoveries are expected as researchers continue cataloging the archive. 2

Why does the archive stop around 2013?

The files reportedly come from Valve's older Steam2 content delivery infrastructure, which was used before Steam moved to its newer SteamPipe system.

That transition helps explain why the archive mainly covers material from 2003 through 2013. It is essentially a snapshot of an older period of Steam's development and distribution infrastructure. 3

More discoveries could still be coming

The archive is reportedly around 12TB in size, meaning researchers have only started going through what could be one of the largest collections of old PC game development material ever publicly examined.

For now, the biggest confirmed discoveries include early Portal 2 content, F-Stop material, an early Left 4 Dead build, early CS:GO content and the Weaponizer model associated with Half-Life 2: Episode 3.

The Half-Life discovery is particularly interesting, but it should not be confused with a recovered Episode 3 game. No complete playable Episode 3 build has been publicly verified at this time. 4

With researchers still examining the 12TB archive, additional unreleased builds, prototypes and development assets could emerge in the coming days.

What the 12TB Steam leak contains so far

• Portal 2: July 2009 beta content and unused gameplay ideas
• Half-Life 2: Episode 3: Weaponizer related asset, but no confirmed complete build
• F-Stop: Early Portal universe project material
• Left 4 Dead: Early June 2008 development build
• CS:GO: Early maps, UI, weapons and gameplay concepts
• Third party games: Early builds and development files from multiple publishers
• Archive period: Approximately 2003 to 2013
• Reported size: More than 12TB