The Jedis are all but extinct, the Old Republic is in turmoil and the threat of the Death Star is looming in Rogue One, fans learned at Star Wars Celebration in California on Sunday.

Director Gareth Edwards, who made Godzilla, introduced a tantalizing concept reel to preview the mysterious film, which is part of a series of films exploring other stories outside of the core Star Wars saga.

“For more than 1,000 generations, the Jedi Knights were the guardians of peace and justice in the Old Republic. Before the dark times. Before the Empire,” the voiceover reads, as the camera tracks to show a ghostly Death Star hovering in the clouds.

The video followed the release earlier in the week of a new trailer for the new Star Wars film proper, The Force Awakens, which caused great comment around the movie world.

Set between the third and the fourth movies in the Star Wars saga, the film will follow a band of resistance fighters who unite to steal the Death Star plans and “bring a new hope”, referring to the subtitle of the original Star Wars.

Felicity Jones, who recently garnered an Oscar nomination for her role in The Theory of Everything, is the only confirmed cast member for the film, which will shoot in London this summer for a 16 December 2016 release. Jones will play a rebel soldier, Edwards said.

Edwards said that her character will not just be a stoic soldier, but a complex, fully rounded human.

“We wanted to see fear, warmth, all of those aspects that everybody has,” he said, saying he was excited that Jones embodies “the complete package”.

In the world of Rogue One, Edwards said the “absence of Jedi is omnipresent”.

The characters in the film realise that the “gods are not coming to save us”, he said. “It comes down to a group of people who don’t have magical powers who band together to bring hope to the galaxy.”

The new trailer for The Force Awakens, JJ Abrams’ new Star Wars film. Guardian

Cinderella scriptwriter Chis Weitz wrote the screenplay, based on an idea from visual effects supervisor John Knoll.

Josh Trank, who is set to direct the next, still-untitled Star Wars anthology film, did not attend, although he was originally scheduled to appear.

Kiri Hart, vice-president of development for Lucasfilm, said that the anthology films would vary in “scale and genre”.

“We wanted freedom to do some films that would be able to stand on their own and tell unique stories,” she said. “They can still feel like Star Wars and be Star Wars.”