Steam API Glitch Exposes Kingdom Hearts IV World List and Unannounced Titles

Key points

• Exophase owner Mike Bendel attributes the leak to a Valve error, not malicious intent, where private achievements became accessible via the API.
• The leak exposed titles including Fable, Judas, Kena: Scars of Kosmora, and Professor Layton vs. Phoenix Wright: Ace Attorney.
• Kingdom Hearts IV world names revealed include Quadratum, Haunted Mansion, Galaxy Far, Far Away, Land of the Dead, Monochrome Origins, Savanna Central, Toy Box, Scala ad Caelum, and Imagineer Planet.
• Square Enix has only officially confirmed the Coco world, but the leak suggests a broader scope of Disney and Pixar locations.
• Kotaku has contacted Square Enix for comment regarding the unauthorized disclosure of pre-release information.

Background

Kingdom Hearts IV is scheduled for release in late 2027, with director Tetsuya Nomura confirming the timeline in August 2026. Previous leaks in September 2026 also hinted at a Nintendo Switch 2 launch, though unverified. This incident follows a separate 13TB Steam data leak in early September 2026 that exposed historical Valve prototypes and beta builds from 2003 to 2013.

Why it matters

The leak provides the first concrete look at the scope of Kingdom Hearts IV's Disney integration, confirming fan speculation about specific franchises like Star Wars and Zootopia. It also highlights vulnerabilities in Steam's API that can inadvertently expose unreleased content from major publishers, potentially impacting marketing strategies and release windows.

What to watch

Square Enix and Valve are expected to address the leak, potentially patching the API error. Official confirmation of the revealed worlds and unannounced games may follow, or the information may remain unverified until official announcements. The leak may also influence the timing of future marketing campaigns for the affected titles.