Steam leak exposes Persona 6, Kingdom Hearts 4 and other unreleased games

September 11, 2026·3 min read

Achievement data for several unreleased and unannounced PC games has appeared online. The information became accessible through Steam’s API even though it was not meant to be public.

The affected titles include Persona 6, Kingdom Hearts IV, Fable, Gears of War: E-Day, and Silent Hill: Townfall. Achievement-tracking site Exophase collected the data after it became accessible on September 8.

Persona 6 and Kingdom Hearts 4 contain spoilers

Persona 6 artwork shows a group of stylish characters in green lighting with a city skyline behind them. — Atlus

Persona 6 is one of the most notable games affected because Atlus has shown relatively little about its story. Its exposed achievement list reportedly includes references to characters, locations, progression systems, and campaign events.

Kingdom Hearts IV was affected as well, and its achievement data appears to reveal Disney worlds that Square Enix has not yet announced. Anyone trying to avoid spoilers for either game may want to avoid searching for the leaked achievement lists.

Other affected titles include Control Resonant, Tomb Raider: Legacy of Atlantis, Mega Man: Dual Override, Ace Combat 8: Wings of Theve, and Persona 4 Revival. The amount of exposed information differs between games.

Steam’s API exposed data that was meant to stay private

Exophase owner Mike Bendel said the site’s automated systems discovered achievements that would normally remain private. Some games also appeared through Steam App IDs without public names attached.

Exophase appears to have collected the information through Steam’s existing API rather than by accessing Valve’s systems directly. The tracking service already uses that API to gather achievement data.

Valve has not publicly explained what caused the exposure. It has also not confirmed whether every listing represents a current game still in active development.

Unannounced listings may include old or unfinished projects

Minecraft Dungeons II heroes fight blocky enemies inside a glowing dungeon filled with blue light — Mojang Studios

The leak also includes entries apparently tied to unannounced projects such as Minecraft Dungeons II, Deus Ex Remastered, and Thief: The Dark Project Remastered. Those names should not be treated as confirmed announcements.

Steam backend data can include cancelled projects, internal tests, old builds, and placeholder names. One unidentified listing was initially connected to Balatro, but creator LocalThunk later said it was unrelated to the game.

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Valve has not commented on the leak

The achievement lists began spreading widely online on September 9. Publishers including Atlus and Square Enix have not confirmed the leaked details.

The information has not been officially confirmed by Valve or the developers involved. The biggest immediate concern for players is that unreleased story details from major upcoming games are now circulating publicly.