A colossal leak of approximately 13 terabytes of Steam depot data, which surfaced online around August 29, has exposed a vast collection of prototype builds for numerous games, including significant first-party Valve titles. The trove of information reportedly spans from 2003 to 2013, with researchers still cataloging its extensive contents.
While no playable builds of highly anticipated titles like Half-Life 3 or Half-Life 2: Episode Three have been found, the leak does contain Half-Life related assets. Notably, a model for the "weaponizer" gun, previously associated with Half-Life 2: Episode Three, has appeared within a Portal 2 prototype build, seemingly serving as a placeholder for the game's Paint Gun. Unconfirmed reports also suggest the presence of filenames related to "ep3" within the data.
The most significant discoveries appear to stem from Portal 2, with at least two prototype builds from 2009 and 2010 unearthed. The 2009 build offers an early look at the game's introductory sequence and includes cut dialogue and placeholder models, such as a picture of a rat. The 2010 build, however, showcases functional versions of three scrapped mechanics: Adhesive Gel, the Paint Gun, and a slow-motion, bullet-time ability. These features were previously only alluded to in the game's developer commentary.
Early builds of Counter-Strike: Global Offensive have also been identified, with at least three distinct prototypes discovered. These builds feature PlayStation 3 and Xbox 360 icons, suggesting they were work-in-progress console ports. Scrapped character models, including one of a woman, and a notably different, cleaner HUD design with cut weapon animations have been found. One build even contains "family guy ragdoll physics." Additionally, several cut maps in these CS:GO prototypes appear to be inspired by maps from the original Left 4 Dead, though they seem to be recreations rather than direct copies.
Left 4 Dead 2 is represented by at least two prototype builds, though they are described as buggy and prone to crashing. These builds reveal minor curiosities such as a significantly higher jump height and placeholder audio in the Dark Carnival level. Intriguingly, most of Left 4 Dead's original maps are included, allowing them to be played with Left 4 Dead 2's survivors, likely for testing purposes.
The leak also contains assets from "F-Stop," a canceled prequel to Portal that was explored during Valve's 2007 "Directed Design Experiments." While a full prototype of F-Stop is absent, some of its assets have surfaced within the Portal 2 prototypes. These include evidence of zombie elements and almost ten minutes of placeholder dialogue for Cave Johnson, which references a "Aperture Science Spirit Camera" and instructs the player to "take pictures" of his "big old butt," indicating a different direction for the game than the final Portal 2. This dialogue suggests that F-Stop's development did influence some of Portal 2's puzzles and assets.
The sheer volume and nature of the leaked data provide an unprecedented look into Valve's development processes and shelved ideas from a decade ago.