When Shigeru Miyamoto first created a princess-rescuing plumber more than four decades ago, Nintendo's future mascot was just a collection of pixels who didn't have a flamboyant Italian accent -- or even a name.

This Wednesday, Mario, now the most famous character in video game history, stars in "The Super Mario Bros. Movie," a major new animated film released in theaters by Hollywood giant Universal Pictures.

"I don't think anybody thought Mario would be this big, including myself," legendary game designer Miyamoto told AFP.

"It's like seeing a 2D illustration come to life as a 3D puppet, and then that coming to life, becoming a human."

The movie -- released in the wake of recent, successful video game adaptations such as "The Last of Us" --- is the second attempt to bring Mario to the big screen, after an ill-fated, live-action 1993 movie.

Back then, Nintendo handed over creative freedom to Hollywood producers, who delivered a bizarre dystopian fantasy set in a dinosaur kingdom.

This time the Japanese gaming giants took no such chances.

Nintendo dispatched Miyamoto himself to co-produce the movie along with Chris Meledandri, founder of Illumination -- the Paris-based studio behind "Despicable Me" and "Minions."

"We wanted to develop the movie ourselves, instead of licensing it," recalled Miyamoto.

"That's when we met Chris. If Chris and his team would develop this together with us, we would feel confident."

But in order to successfully bring that authentic Nintendo spirit to the movie, "I was certain that we needed to be involved, otherwise it could not be done," said Miyamoto.

- 'Character-driven' -

The result is a colorful, kaleidoscopic action movie, frenetically paced to appeal to children, but stuffed with winks and nods to the games that generations of nostalgic Nintendo fans grew up with.

It even offers its heroes an origin story.

The Mario brothers, struggling to get their fledgling New York plumbing business off the ground, try to save the city from a flooding crisis, but get sucked down a green warp pipe.

Mario ends up in the Mushroom Kingdom, where he sets off to save Luigi after learning that his more timorous brother has landed in Bowser's clutches.

According to Miyamoto, the idea for a film emerged from a major strategic shift by Nintendo around a decade ago, to make its games "more character-driven."

Until then, beyond the odd "Wahoo!" catchphrase, Nintendo designers would not add "anything extra or unnecessary" to characters, because "we didn't know what kind of games they would be used for" next.

But "we wanted people who are not gamers to recognize our characters," explained Miyamoto, leading to the partnership with Meledandri's Illumination studio.

The "change in direction" also prompted the Nintendo theme parks that recently opened in Osaka and Los Angeles, with more to come.

- 'Spielberg' of video games -

For Miyamoto, now 70, who is sometimes billed as the Steven Spielberg of video games, his new role as a Hollywood producer was something of an adjustment.

"I enjoy films. I'm not a film expert," he told AFP.

"I do watch a variety of movies. But I never thought I would want to make a movie."

Instead, films like Spielberg's "Indiana Jones: Raiders of the Lost Ark" had inspired Miyamoto's video games, which include the critically adored "Legend of Zelda" series.

"When I watched it, I could tell that so many creative people were involved... and the direction of that single lead person brought it together into this one cohesive structure," he recalled.

"I was looking at that from a game designer perspective, thinking 'I want to make games like that!'"

Working closely with Meledandri for six years and watching the Hollywood mogul bring the new "Mario" movie together, Miyamoto got to "witness that whole process happening in front of me."

A-list stars including Chris Pratt, Jack Black, Anya Taylor-Joy and Seth Rogen signed on to voice Nintendo's famous roster of characters. 

- 'Possibilities' -

The movie has weathered controversy, not least over Mario's accent.

While in the video games, Mario has a famously over-the-top Italian twang, many fans watching the new film's trailer last year were baffled to find Pratt speaking in an American accent.

An explanation for that apparent oversight is woven into the movie's plot, and should help to assuage some of viewers' skepticism.

Pratt has suggested that Mario's traditional accent -- voiced in the games by Charles Martinet -- could prove distracting across a feature-length film.

"We discussed early on the importance of grounding my version of Mario's voice in something that could carry a 90-minute emotional through line," he said, in the film's press notes.

Miyamoto says he hopes that Mario being in a movie will make it feel to fans like he actually exists.

"I feel that we have accomplished that. I hope that we've accomplished that." 

With a major Mario movie completed, could there be a space for future big-screen Nintendo adaptations, such as a "Zelda" film?

"There's always possibilities!" said Miyamoto.

amz/hg/bfm