"The basic scenario and story concepts haven't changed that much," she explains, speaking through a translator. "They're quite similar to what they were originally. There have been some changes, small scenario tweaks and the game's functionality itself has changed. But overall, from a musical perspective, the concepts that we wanted to use from the start, they're pretty much as they were. It's kept on the same theme, basically."

I'm meeting Shimomura at London's iconic Abbey Road Studios. We're in a room overlooking Studio One, where the London Philharmonic Orchestra will be performing the game's tracks later that evening. It's a cramped, gloomy space -- a typical refuge, I suspect, for sound engineers -- filled with squishy chairs, mixing desks and other high-end recording equipment. The downbeat atmosphere has had little effect on Shimomura's mood, however. She's a calm, dignified bundle of sunshine. Always cheerful, always smiling.

"I've been a fan of Final Fantasy for a long time, and I never thought that I would get the chance to do it," she says. Shimomura is an industry veteran, having worked with Capcom, Square Enix and Nintendo for almost 30 years. Final Fight. Street Fighter II. Super Mario RPG. Breath of Fire. Kingdom Hearts. The list goes on and on. During that time, she never once considered what her own Final Fantasy score would sound like. Not until Square Enix called, anyway. "It wasn't, not having a desire to want to do it professionally," she offers. "It was just such a surprise."

The franchise is steeped in history. Whether it's the "Theme of Love" from Final Fantasy IV, or "One-Winged Angel" from Final Fantasy VII, every game has its share of memorable, distinctive tracks. Sweeping scores that underscore tense, mystical battles. Delicate melodies that reinforce a party member's sadness, confusion or unrequited love. The tracks stand on their own but take new meaning when you know the characters, locales and events they were originally paired with. Many are the work of Nobuo Uematsu, one of the most respected video game composers of all time.

Nobuo Uematsu performs at La Cigale in 2012. Credit: Redferns via Getty Images

No pressure for Shimomura, then. Final Fantasy XV, which comes out at last on November 29th, is a slight departure from previous games. The combat is faster and more "active" than before. The universe is a curious blend of high fantasy and contemporary technology; modern skyscrapers and sleek sedans surround individuals who can teleport, cast spells and wield magical weapons. Smartphones and pinball machines exist alongside colossal, lumbering monsters. Similar contrasts can be found in other Final Fantasy games -- Final Fantasy VII and its depiction of Midgar, for instance -- but here, it's a new take.

Shimomura loves this idea. She points to the steampunk elements of earlier Final Fantasy games and how they were paired with traditional fantasy tropes. Final Fantasy XV, she says, is "not quite as different as some people say." It's edgy and experimental but also respectful of the franchise's long-held traditions. (Crystals! Chocobos! Summons!) That same philosophy can be applied to the new game's soundtrack. "That's how I approach, personally, the making of the music," she says, "and I think that's what makes the franchise. That attempt to keep a universal fantasy style of music but mix in new themes and influences each time."

Final Fantasy XV is no exception. American blues, for instance, can be heard in some of the game's locations. Bossa nova, a Brazilian style of music combining samba and jazz, plays jubilantly while Noctis and his friends set up camp. Both genres are unusual for Final Fantasy, adding another dimension to the world and your actions within it. As Shimomura explains all of this, her voice starts to quicken. Maybe it's excitement, or pride. After 10 years of waiting, I would have both in abundance.

Each new track is a collaboration between Shimomura and the studio. Most started as a request from the writers -- a song that was needed for a particular cutscene, battle or locale. Shimomura would go away, work on a demo, and then send it to the team for review. Some songs were given the okay immediately while others required a little extra work. The specifics were debated "quite late at night" on conference calls. "A lot of back and forth was done by email as well," she says. "But I certainly did discuss with them. What went in and what small changes needed to be made."

Her involvement extended to the recordings too. Some of Final Fantasy XV's music was performed in Boston; Shimomura traveled there twice to listen and provide feedback in person. "Obviously, it's quite difficult to get into every single session from there, so we set up a remote video satellite link, and I've been listening in real time from Japan. But generally I do like to participate and take part in all of the recordings," she says.

Soon, Shimomura will hear those tracks once more. Only this time, the public will be able to listen to them, too. A small audience has been invited to Abbey Road Studios while thousands, possibly millions, watch a livestream at home. After a decade of toil, of suspense, I can think of no better tribute to Shimomura and her contributions to the game.

Who knows if Final Fantasy XV will live up to fans' expectations. Final Fantasy XIII and its direct sequels were, for many, a low point for the franchise, with a story that made little sense and characters that were difficult to care about. Square Enix is aware that it needs to bounce back -- this time, there's no room for mistakes. And while the quality of the game is a mystery, there's one statement I can make with absolute confidence: With Shimomura at the helm, the music is in capable hands.