For Mr. Savini, who struggled with dyslexia as a child, the wizards, elves and paladins of Dungeons & Dragons had been a portal into the world of storytelling. For Mr. Pascal, it was his creative spark. “I would not be a filmmaker if it weren’t for D&D. Plain and simple,” he told an interviewer this year. (Mr. Sprattley was more of a “noob,” short for “newbie,” Mr. Pascal wrote in their first Kickstarter update.)

In many non-teenager circles, it is not quite the thing to admit that Dungeons & Dragons changed your life. But the filmmakers spoke of their subject with enthusiasm approaching veneration. When Mr. Savini heard about the game’s history, he said in their Kickstarter pitch video, “There was a moment of awe, and then there was a moment of, ‘Do I want to go any further? Would I break the illusion by looking into this game?’ ”

Hoping to finish by this year, the game’s 40th anniversary, they began hunting down all the relevant authorities: Mr. Gygax’s relatives; game designers who had helped build Mr. Gygax’s company, Tactical Studies Rules, which published the game’s first set of voluminous rule books in 1974; and Dungeons & Dragons historians, who argue that its major innovation — individual role-playing — made shinier successors like World of Warcraft and even websites like Facebook and OkCupid possible.

Even as they prepared to raise funds through Kickstarter, however, tensions simmered. In June 2012, Mr. Pascal wrote in the affidavit, Mr. Savini “accused James and me of trying to steal his movie after we, as part of our job, merely offered suggestions for a possible narrative for the film.”

Mr. Savini followed up with a chilly email saying he had a rights dispute with collaborators on a previous film. “So I know what it looks like,” he wrote. “All the warning signs showed up within a 24 hour period.”

At the time, Mr. Pascal wrote, the director kept refusing the producers’ requests to see the footage. Mr. Savini acknowledged in an interview that “there were definitely some issues between the two of us,” but declined to say more about the dispute.