Anyone familiar with the Kingdom Hearts franchise knows that it's in many ways a love letter to Disney. The attention to detail that Square Enix puts into every bit of Kingdom Hearts 3 shines through, a fitting follow-up to a beloved franchise. Needless to say, it's understandable that in order to produce such high-quality work Square Enix communicates directly with Disney throughout development. And it's also understandable that sometimes the Disney approval process can result in certain struggles, which is now known to be the case with regards to Pixar's Toy Story.
Speaking with IGN, Kingdom Hearts director Tetsuya Nomura described Pixar as being more interested in the "technical, creative side of things" compared to Disney's "overall production" approach. Nomura even described Square Enix as more akin to Pixar in this regard. The result, however, was that Square Enix and Pixar had to work out certain issues before even starting to move forward on Kingdom Hearts 3.
Kingdom Hearts, according to Nomura, historically has Sora, Donald, and Goofy travel to each world in a canonical capacity:
"When I first brought this to Pixar and I asked about doing that, they were like, 'Actually, no. The Toy Story story is complete. It's a complete package the way it is, and we can't really change that.' I told them if I'm going to do this in the Kingdom Hearts way, then it's going to become a case of, 'Actually, Sora and his friends did come into the world.' "
The result was that Kingdom Hearts 3 would fit its Toy Story world canonically in-between Toy Story 2 and 3. Kingdom Hearts 3 also manages to find a way to tell an in-universe story that's separate from the normal goings-on of Andy's room and its dozens of characters. Pixar ultimately approved the approach, even accepting that the events of Kingdom Hearts 3 fit into the animated series' canon.
Those who have played through Kingdom Hearts 3 will likely be able to see the extent of Pixar's more limiting influence in both the Toy Story and Monsters, Inc. worlds. Neither world retells events from their original films, like the Tangled, Frozen, and most other worlds do, and neither results in any consequential events, like the Hercules and Big Hero 6 worlds.
What matters the most is that Square Enix felt it did Pixar's worlds justice in the end. And as animation director Koji Inoue describes, there's no better validation than Pixar's own animators complimenting their work:
"The feedback was always, 'It looks so nice to have it in such high quality.' It was actually to the extent where Pixar was saying that some people who'd seen it were saying, 'Wait are you guys making a new movie?' Because it was exactly like it was supposed to look like."
Kingdom Hearts 3's visual quality really speaks for itself. While there is definitely some criticism about the game's story, few can argue that Square Enix has vividly recaptured the beauty of Disney and Pixar's art in both its cinematics and gameplay.
Kingdom Hearts 3 is available now on PS4 and Xbox One.