When Disney held its annual D23 fan convention in Anaheim, California, last week, news was dominated by the announcement of new Star Wars-themed areas for its giant theme parks, promising fully immersive adventure experiences. But when it came to video games, neither of Disney’s big geek-friendly franchises – Star Wars or Marvel – dominated the show. Instead, the spotlight was very much on franchise far less recognised by the wider masses: Kingdom Hearts, an action-RPG series that crosses Mickey Mouse, Donald Duck and Goofy with elements of the Final Fantasy series.

When new material for the much-delayed Kingdom Hearts III was revealed during the gaming-focused Level Up panel, the cheering was louder than anything that greeted major mainstream properties such as EA’s Star Wars Battlefront II or Insomniac’s upcoming Spider-Man title. While Kingdom Hearts is celebrating its 15th anniversary this year, it’s been a 12-year wait for a brand-new, main instalment in the series.

For all the fervour surrounding the series now, this ostensibly odd tie-in title once seemed like a risky prospect. When it launched on the PlayStation 2 in 2002, it had to overcome not only the strange mix of Western cartoon characters with Japanese fantasy scenarios, but was fronted by a trio of original characters – Sora, Kairi, and Riku – who were juvenile even by Japanese RPG standards. It also told an almost hopelessly complex story where worlds based on Disney films were being devoured by an evil force known as the Heartless, and Sora teamed with a magic-using Donald and a physically powerful Goofy to defeat them. To many observers at the time, it seemed doomed to failure, or at least obscurity.

Instead, it proved a major hit, initially in its native Japan but increasingly so in the west, where Disney affection reigns supreme. With success came a direct sequel, also released for the PS2 in 2005, and while Kingdom Hearts III itself has been in absentia, players’ time has been spent on almost a dozen games telling side stories and history to the universe, expanding on the lore and background.

Facebook Twitter Pinterest The original Kingdom Hearts Photograph: Disney/Square Enix

This “trilogy” of roughly a dozen games – the numbering gets fuzzy when re-releases, enhanced ports, and Japan-only mobile games are factored into the equation – has surprisingly humble origins though. What is now an international franchise worth millions and capable of attracting fans devoted enough to brave cosplaying in the California sun in July, began with a literal elevator pitch.

“The Square Enix Japan office happened to be in the same building where Disney’s gaming division was,” recalls long-time series director Tetsuya Nomura, who appeared on the D23 panel, and was visibly moved by the crowd reaction. “It just so happened that our executive producer, Mr Shinji Hashimoto, and a Disney executive rode the elevator together.”

“They would have conversations saying, ‘Wouldn’t it be nice for us to do something collaborative?’ So rather than having either Square or Disney approach the other with a formal business plan, it was all down to being in the same building!”

Fast forward 15 years, and Kingdom Hearts has taken players to more than two dozen worlds based on Disney films, both animated classic and live action favourites such as Tron and Pirates of the Caribbean. Yet that key ingredient, traversing the Disney multiverse and meeting beloved characters, has also been one of the biggest obstacles to Nomura’s vision for the series.

“If anything, the biggest challenge [in creating Kingdom Hearts] may be trying to converse with Disney.” Nomura says. “With Final Fantasy, from a creator’s perspective, it’s a very free title, free to create. Each title is different, and there’s not much in the way of limitations for the numbered instalments in the series. I’d been with the Final Fantasy team for most of my career; I’d always been involved in their production. In my mind, the way to create a Final Fantasy, the formula if you like, is ingrained.”

Disney’s very different – and decidedly American – corporate structure, plus the shifting tides of the Mouse House’s movie distribution deals and studio buyouts, has sometimes stymied Nomura’s plans for the game series, leading to lengthy pitching processes for the worlds Square Enix uses in each game.

It’s because of this back-and-forth and decidedly unmagical legal red tape that it took Nomura over a decade to bring Kingdom Hearts’ newest world into the fold. The wait should prove worth it for fans of both the game and the film studio though, as Kingdom Hearts III will see Sora and his allies travelling to the world of Toy Story – the first time a Pixar property has appeared in the series.

“Just to get Toy Story approved with Disney took a long time. I’d wanted to use the film in Kingdom Hearts for over 10 years, since I was in development on Kingdom Hearts II,” Nomura explains. “It was only a couple of years ago, shortly before we moved on to developing Kingdom Hearts III, that we finally got an opportunity to speak directly with Pixar.”

Nomura puts the delay largely down to the Disney of 2005 only distributing Pixar’s films, rather than fully owning the studio. Disney’s complete purchase of the CGI animation house in 2006 paved the way for Toy Story’s inclusion in Kingdom Hearts III, with the property being one he wanted to save for the trilogy capper.

Facebook Twitter Pinterest Kingdom Hearts III Photograph: Disney/Square Enix

Perhaps the biggest draw for non-gaming fans, or those new to the series, is that the new Toy Story world will feature an original tale for the beloved animated characters, with Woody, Buzz and the rest of Andy’s toys helping Sora investigate a new invasion of Heartless. The chapter – which was overseen by Pixar’s story and character teams, and ultimately given the blessing of original Toy Story director John Lasseter – will also find Sora, Donald, and Goofy taking on appropriate action figure-styled forms, exploring the world at the same scale seen in the movies. Beyond the Heartless, fresh peril awaits in tackling enemies based on the sadistic Sid’s cadre of tortured toys, tapping into the darker elements of the film.

It won’t be the only CGI film to be reflected in the new game, either. Toy Story will be joined by recent in-house Disney movies such as Tangled and Big Hero 6, with Rapunzel’s magical hair and the super powered heroes of each property factoring into the gameplay of their respective worlds.

Adapting CGI animation has another benefit for the game’s development – they’ll be able to utilise perfect character models already meant for a computer animated world, meaning the finished product will look exactly as viewers will remember from the films.

“With a CG animated film, you have a reference image. You know what to aim for in terms of the aesthetic, so there is that,” Nomura reflects. “Especially with Toy Story, we feel that we were able to recreate it as closely to the original film as possible.”

Facebook Twitter Pinterest Kingdom Hearts III will transpose familiar Final Fantasy gameplay into favourite Disney locations, such as Andy’s front yard Photograph: Disney/Square Enix

The concern now will be whether, after skipping an entire console generation, new players will find the ambitious sequel accessible. Nomura himself is hopeful.

“With any Kingdom Hearts game, there are so many different elements. Some players might want to engage with the story. Others might want to enjoy the gameplay experience, or some might like exploring the settings of the world – it depends on where the player wants to put their emphasis. There may be some areas of the story players are not familiar with, but I’m hoping that piques their interest to go back to previous titles to learn more about the world, I do feel that even if you started with Kingdom Hearts III, it would be enjoyable in and of itself.”

With the expensive and ambitious Disney Infinity series now axed, there is a lot more expectation on Kingdom Hearts to be a success. As a 25-year veteran of the games industry, joining developer Square as a debugger on Final Fantasy IV in 1991, before becoming a designer of monsters and battle graphics on Final Fantasy V, Nomura has faced plenty of pressure in the past. But his emotional response to that D23 applause tells us how much this curious game matters now.