Disney has put a lot of emphasis on exactly how radically different Rogue One's tone is from the rest of the Star Wars universe.

This is the franchise's gritty war film and the proof is in the pudding; director Gareth Edwards' touch is keenly felt in its muted landscapes, in AT-ATs looming out of the mist like vengeful metallic Godzillas (he directed the 2014 film).

A risk, perhaps, but the studio has proved with Rogue One that the Star Wars universe possesses infinite potential - it's a major turning point for the entire franchise and a drastic move that was very consciously chosen by Edwards and his team.

The film's IMAX featurette sees Edwards explain, "We started playing around with ideas and the thing that just crept to the surface really easily was this idea of a slightly more realistic Star Wars."

"One of the little things we did as an experiment was take war photography from Vietnam and the South Pacific and the Middle East, and photoshop Rebel helmets on the soldiers and replace some things with stormtroopers in the background, and instead of Hueys - it was U-wings or X-wings. And we looked at these images and they were really engaging. You really thought, this is emotional and this feels real."

Rogue One: A Star Wars Story Clip - Trust Goes Both Ways