SAN FRANCISCO - Rogue One: A Star Wars Story is darker and different from any other film in the franchise-which, at their core, are heroic tales of derring-do for all ages.

But with Rogue One, we seem to have the combination of a war movie and a heist film.

It actually puts the Wars in a Star Wars movie.

"We essentially got a license to be different with this movie and take a risk," director Gareth Edwards said at the film's exclusive press event. "The great thing about being a standalone film (is) we don't really have to exist for other movies to continue. So, we could be brave-and that's what we did."

"We just tried to make the most realistic version of Star wars that we've seen and use a lot of different techniques (to achieve that)," he said.

"I feel like in terms of Star Wars (films) that I love tonally, I guess (the one we were aiming for) was something like The Empire Strikes Back," Edwards continued. "But our movie, even though we take it quite seriously, there's a lot of subtle humor in it. The key thing, though, is that it's about trying to achieve something."

Edwards said that the diverse cast, who hardly know each other when the film begins, are united by a singular goal: Stop the construction of the planet-killing Death Star-or at least find its flaw, so that it can eventually be destroyed.

"The story behind the movie is (that) all these different people from all these different backgrounds have very little in common, (but) they believe in a good future for the world," he said. "We are all better off when we work together than on our own."