A Dead Mobile Game Is Now Key to Kingdom Hearts 4

Only Kingdom Hearts could make a dead mobile game required homework for its next numbered sequel. The latest Kingdom Hearts 4 trailer features several characters who originated exclusively in Kingdom Hearts Union X Dark Road, a mobile prequel that was delisted from digital storefronts in 2024. As of right now, Square Enix hasn't released any official way to catch up on that game's story.

Union X Dark Road was a dual package covering the ancient Keyblade War that set the entire series in motion, plus the origin story of long-running antagonist Xehanort. It's not filler lore. These are foundational events the series has been building toward for years, and Kingdom Hearts 4 appears to be pulling directly from them. If you weren't playing a free-to-play mobile game that no longer exists, you're walking into the next mainline entry missing context that clearly matters.

Square Enix has done this before. Ahead of Kingdom Hearts 3, the company bundled cutscenes from harder-to-access titles into remaster compilations, turning them into watchable movies. Fans are hoping for something similar here, and the timing could line up: a full Kingdom Hearts collection is coming to Switch 2 digitally on October 8, 2026, with Kingdom Hearts HD 1.5+2.5 ReMix also launching on the original Switch. A Game-Key Card release will also be available for Switch 2. But none of those collections include Union X Dark Road's story content. In the meantime, fans have uploaded the game's cutscenes to YouTube, which is currently the only way to experience them.

I get that Kingdom Hearts has always treated every entry as canon, and I actually respect the commitment. But there's a difference between asking players to track down a PSP game and asking them to have played a live-service title that Square Enix itself pulled from storefronts. The series started on PS2 in 2002; nobody was thinking about digital delistings back then. Now it's a real problem, and Square Enix hasn't acknowledged it.

Kingdom Hearts 4 still has no release date. It's confirmed for PC, PS5, Switch 2, and Xbox Series X/S.