They will be using CGI characters, but it sounds like they hope to do a better job of it this time around. The 90s digital camera footage would be unusable for a modern game, beyond recasting and refilming I don’t see any other feasible way to make the FMV not look out of place in a modern game.

From gameinformer

One of the biggest technical challenges for Anderson and Gamiel has been bringing Riven’s characters back to life. The original game featured live-action video performances by several actors, including Rand Miller as Atrus, Sheila Goold and Regina Altay as his wife Catherine, and Royal Shakespeare Company alumnus John Keston as his father Gehn.

But it’s literally impossible to graft a 2D video from 1997 into a real-time, high-resolution 3D environment. Cyan’s previous remake, 2021’s award-winning VR and PC version of Myst, featured computer-generated characters in lieu of the original live-action performances. “It was… an experiment,” Miller laughs, but for the new Riven, Cyan hired a full-time animation lead, Autumn Palfenier, to raise the uncanny valley.

“For Gehn, we tried analyzing the [old] video and tracking certain features, but the resolution was so low, and it’s not even a full shot, so it just wasn’t doable,” Anderson says. Instead, they’ve been filming performances in Cyan’s basement using motion-capture technology.

“I can say on the record that this is a union production with SAG-AFTRA,” Gamiel says, referring to the same labor guild that represents Hollywood actors. “We wanted to get some incredible talent into this game.”

She won’t tell me who’s playing who but does confirm that Miller will return as Atrus and that the studio managed to salvage an old audio recording of John Keston, who died from COVID-19 complications in February 2022 at the age of 97. “We had an actor study John’s performance and then do it in sync with the original audio, so we got Gehn’s full body,” Anderson says. They show me a work-in-progress close-up of Gehn’s face, which exceeds my expectations.