Nintendo was all about "transformation" at E3 this year, but the most passionate members of the gaming community might balk at their favorites jumping into new directions.

If you asked Nintendo of America President and COO Reggie Fils-Aime about his company, he'd say it's in the middle of a "transformative" moment.

It was a word he used frequently during Nintendo's streaming-only press conference, which aired at the start of E3 — as well as later, when Reggie Fils-Amie, Nintendo of America's president and COO, spoke to Mashable.

By "transformative," Fils-Aime wasn't just referring to Nintendo's big announcements of 2015 — that the company is putting its games onto mobile for the first time, working on a new console, and building a theme park in Florida. Transformation is also a running theme when it comes to how Nintendo is handling fan-favorite franchises.

"We're taking our great IP and transforming them and making them new again — making them fresh and appealing for the fan who feels they know the franchise. But we're giving them new things to enjoy," Fils-Amie told Mashable at E3.

That's a familiar sentiment in gaming. Game re-imaginings are common, and often dramatic; take the recent reboot of the Tomb Raider franchise, which turned the narrative in a darker and more realistic direction.

But Nintendo has a history and a stable of characters that spans more than 30 years. There are fans who have literally grown up with its games — and for these people, transformation can be scary.

See, for example, Nintendo's E3 announcement of Metroid Prime: Federation Force. Metroid Prime was a well-loved and critically-acclaimed first-person shooter that featured exploration and environmental puzzles. The trilogy of games included in that series was thought of fondly as the perfect bridge to bring the franchise into modern 3D game worlds. For at least five years, fans have been asking for a new entry into the Metroid universe, one that was similar to the originals in quality and plot.

So when this trailer for Federation Force came up during Nintendo's E3 stream, fans were not happy.

Sure, it's Metroid Prime in name only — but the game strips out all the single-player exploration in favor of a cooperative shooter. The genre-bending goes way too far in the eyes of fans, especially since the trailer doesn't explain how this fast-paced shooter, which is only for the 3DS handheld, fits into the Metroid world.

How mad are fans? The trailer has about 7,000 likes, but about 69,000 dislikes.

"What the fan at home saw was something in the Metroid Prime universe that they weren't expecting. The reaction has been negative. There's no sugar coating it," Fils-Aime acknowledged.

"This is an example where fans who aren't able to get their hands on the game may be at a bit of a competitive disadvantage. Everyone who has played what we are showing regarding Metroid Prime, they've come across really pleased," he continued. "My ask is that fans trust us."

But Federation Force isn't the only game toying with a beloved franchise. There's a new Legend of Zelda on the horizon, and Fils-Aime and series director Eiji Aonuma have both promised big changes from the game's traditional format — even though it was absent from E3 this year.

"Mr. Aonuma has said that he is challenging many of the conventional wisdoms of Zelda gaming in this new Zelda, and that's what we do. We believe we have to do that to keep the franchises fresh," Fils-Aime said.

It almost seems like a situation primed for a blow up if fans see something they don't expect, something that's incongruous with their original ideas of a Zelda game.

For perspective, let's look back on 2003's The Legend of Zelda: Wind Waker for GameCube. Fans were originally very upset about the game's cel-shaded animation, since they were hoping for a more realistic looking game. Aonuma even described this cycle in a recent interview with Kotaku as the "Zelda cycle": “Basically, as time progresses, negative opinions about The Legend of Zelda turn into positive ones."

But if Nintendo fans are hoping for a newer version of the same game, they might be setting themselves up to be disappointed — until, as Fils-Aime said, they play the game. In his words:

"We believe that in order to propel the franchises forward, we have to be the ones to constantly challenge the paradigms, challenge the conventional wisdom, challenge what we thought was the essence of the particular franchise, and a particular form of gameplay."