Around 13 terabytes of Steam depot data appeared online on August 29, containing prototype material for a remarkable number of games. The files reportedly include early versions of Valve titles such as Portal 2, Counter-Strike: Global Offensive and Left 4 Dead 2, alongside third-party projects.
The leak, commonly referred to as “Steam2”, is still being catalogued. The depot files appear to span 2003 to 2013, while the circulating torrent contains both first-party Valve builds and third-party game data. Its full scope remains unclear, and further discoveries are expected.
For readers interested in how unfinished ideas shape game hardware and design, RETROCADE’s arcade news and gaming coverage offers more industry-focused stories.
Half-Life material, but no Half-Life 3
The leak has not produced a playable build of either Half-Life 3 or Half-Life 2: Episode 3. It does, however, contain material connected to the latter project.
The most notable find is a model believed to be the “weaponizer” gun from Half-Life 2: Episode 3. Filenames connected to the cancelled project surfaced in 2011, including references to an ice gun, a flamethrower and three weaponizer entries. The Half-Life 2: 20th Anniversary Documentary, released in 2024, later showed footage of several weapons intended for Episode 3.
That footage included the Ice Gun and a fleeting view of an unnamed weapon that fans believe is the Weaponizer. The model also appears in a Portal 2 prototype, where it seems to have served as a placeholder for a discarded Paint Gun. Reports of filenames in an “ep3” depot remain unconfirmed.
Portal 2 prototypes reveal abandoned mechanics
At least two prototype builds of Portal 2 have been identified. The 2009 version is an early work-in-progress, featuring unfinished cutscenes, placeholder assets and an early form of the introduction.
It also contains smaller curiosities, including a rat image triggered by opening a particular door and a cut line in which GLaDOS describes itself as Chell’s “mother”.
The 2010 build is more substantial. It includes partly functional versions of three mechanics removed from the finished game: Adhesive Gel, the Paint Gun and a slow-motion, or “bullet-time”, ability.
Adhesive Gel and the Paint Gun were already known through Portal 2’s developer commentary, but the prototypes provide a clearer look at how they worked. Adhesive Gel allowed the player to walk on walls, while the slow-motion system also altered sound effects when activated.
These experiments are a useful reminder that polished puzzle games often emerge from discarded systems. The same process can be seen when comparing different arcade machine cabinet concepts before choosing a final layout.
Early Counter-Strike: Global Offensive builds
The files appear to contain at least three early builds of Counter-Strike: Global Offensive, although the versions discovered so far are broadly similar.
PS3 and Xbox 360 icons suggest that some builds were work-in-progress console ports. One version also includes discarded character models, including a woman, as well as a particularly clean unused HUD and several cut weapon animations.
One build reportedly contains “Family Guy” ragdoll physics, an unusual experiment that did not make it into the released game.
Later prototype material includes several discarded maps. Some appear to draw inspiration from maps in the original Left 4 Dead, although they look more like reinterpretations than direct copies. The reason Valve abandoned them is not known.
Left 4 Dead 2 prototypes
At least two Left 4 Dead 2 prototypes have been reported. They are said to be unstable, with some levels crashing at fixed points, and the discoveries so far are less extensive than the Portal 2 and Counter-Strike material.
Even so, the builds contain some notable differences. Players can jump considerably higher, and the Dark Carnival concert sequence uses loud placeholder audio. Anyone viewing footage with headphones should take care with the volume.
Most of the original Left 4 Dead maps are also present in the Left 4 Dead 2 builds. This allows them to be played with the sequel’s survivors, presumably for testing.
F-Stop assets inside Portal 2
F-Stop was a cancelled project conceived as a prequel of sorts to Portal. In 2007, Valve spent three months exploring five game concepts in what Gabe Newell called the “Directed Design Experiments”. One of those concepts became F-Stop.
The proposed game centred on photography-based puzzles. Players would take pictures and manipulate their scale to solve problems, a concept that resembles the later game Superliminal. Newell said the team found the idea compelling enough to consider expanding it into a full release, but the project was eventually abandoned and Portal 2 took its place.
No playable F-Stop prototype has been identified in the leak. However, several assets have been found within a Portal 2 prototype. Newell has previously explained that the project influenced some of Portal 2’s puzzles and that its assets were used for testing during development.
One especially revealing discovery is almost ten minutes of placeholder Cave Johnson dialogue. The recording comes from an F-Stop concept rather than Portal 2: Cave instructs the player to collect an “Aperture Science Spirit Camera” and take pictures of his “big old butt”. The material offers a rare glimpse at Valve’s 2007 experiments, including what might have been another performance by J. K. Simmons as Cave Johnson.
As with many large prototype archives, the catalogue is incomplete. More Valve experiments, cut content and development tools may emerge as researchers continue examining the files. For anyone comparing old-school controls and modern interactive displays, RETROCADE also has guides to arcade parts and repair hardware and DIY arcade cabinet projects.
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