Kingdom Hearts 3 is due to be released at the end of January, after a really long development period. The game got announced at E3 2013 with a brief teaser and as fans will surely recall, it was originally meant to be powered by Square's own Luminous Engine (which we've already seen in Final Fantasy XV).

Speaking to EDGE (February 2019, issue 328), Game Director Tetsuya Nomura revealed that the decision didn't really happen because of the developers. Rather, it was decided by higher-ups and ultimately affected the development schedule.

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We had our own company reasons, essentially. It wasn’t something that we had anything to do with, it was decided higher up. It was a whole year that we had to kind of rewind and restart. As a dev tool, Unreal Engine 4 is kind of an all-in-one – it’s got all of the stuff that is needed in it, it’s used around the world, and we also got really great support from Epic Games. They were very helpful through the entire process. It would have been a different story if the team making Luminous had been members of the Kingdom Hearts team. But they were a different team, so that did make things a bit more difficult.

Kingdom Hearts 3 Co-Director Tai Yasue concurred, emphasizing that the developers at Square Enix Business Division 3 had to learn this brand new engine from scratch.

We had to learn a lot. When we started using Unreal Engine 4, we had these study groups – well, not study groups, but we all sort of… There’s a tutorial. I made my own robot, a robot that changed shape. We never used it in the game, we were just testing it out. We had contests too, I remember. Each game designer made something, and we sort of compared it. And this had nothing to do with the game. We had to learn about the engine. That was part of the development timeline and was something that contributed to and affected the schedule.

Of course, it wasn't all bad. The Unreal Engine 4 is known to be fairly easy to get into and Yasue confirmed as much.

The thing with Unreal Engine 4 is it’s really easy to experiment, gameplay-wise. We didn’t need any assets to start off, so the game designers that aren’t artists at all could actually start to test the game.

Kingdom Hearts 3 is out January 29th for PlayStation 4 and Xbox One. No PC version has been announced, but Square Enix has increased its support of the Steam platform over the years and we'd be surprised if the game didn't launch there at some point.