A technical error within the Steam API has exposed achievement data for over 125 unreleased and unannounced video games. The glitch, which occurred on September 9, 2026, has provided the public with an early look at plot points, world locations, and gameplay structures for several major franchises, including Kingdom Hearts, Persona, and Gears of War.
The exposure appears to be a result of a malfunction during Steam’s weekly maintenance. Mike Bendel, owner of the achievement-tracking site Exophase, reported that the data became accessible through the API due to a “screw-up” on Valve’s end rather than a targeted hack. While many of these entries likely use development placeholders, the level of detail in several lists has provided significant insight into unannounced projects.
Major Reveals: Kingdom Hearts 4 and Horizon
The leak for Kingdom Hearts 4 is among the most detailed, suggesting several new Disney-themed worlds that have not yet been officially confirmed. Reported achievement descriptions point toward the inclusion of worlds based on Zootopia, Coco, and The Haunted Mansion. Perhaps most notably, the data indicates a Star Wars presence in the form of the forest moon of Endor, a location long-rumored by fans since the game’s initial teaser trailer.
Sony’s Horizon franchise also saw significant exposure via a title listed as Horizon Hunters Gathering. The achievements characterize this project as a co-op spin-off rather than a traditional single-player entry. The data suggests the inclusion of live-service elements, specifically mentioning a “battle pass” and “epic session weapons,” indicating a shift toward a repeatable, session-based gameplay loop for the spin-off.
Breadth of Affected Titles
The scope of the API exposure extends across several major publishers. High-profile games identified in the leak include:
- Persona 6
- Gears of War: E-Day
- Fable
- Control: Resonant
- Deus Ex Remaster
While many of these titles are known to be in development, the leak confirms their eventual presence on the Steam platform and, in some cases, reveals specific narrative milestones.
According to Forbes, this incident has effectively spoiled marketing cycles for several games, including technical placeholders for Kingdom Hearts 4.
Distinguishing the API Bug from the 12 TB Breach
There has been some confusion regarding the scale of this event due to its proximity to a separate, massive data breach. In August 2026, a 12 TB to 13 TB repository of Valve prototypes and unreleased builds from the era of 2003–2013 was leaked online. That earlier breach focused on legacy assets, such as early versions of Left 4 Dead and Grand Theft Auto 5.
In contrast, the September 9 achievement exposure is a live API glitch affecting current and future software. While some reports have conflated the two under the “12 TB” heading, the achievement data is a distinct, more immediate security and PR concern for active development cycles. As of the afternoon of September 9, Valve has not released an official statement regarding the API malfunction or the resulting data exposure.
