Spoilers for Blade Runner and Blade Runner 2049 below

Like Harrison Ford's character Rick Deckard as he sat in Niander Wallace's water-logged office, Blade Runner 2049 viewers got a shock when Sean Young's character from the original 1982 movie, Rachael the replicant, appeared in the just-released sequel looking fresh as a fabricated daisy.

In the movie itself, the character is confirmed to be long dead. More importantly, in real life the actress Sean Young has aged more than 30 years since the original Blade Runner's release. In Blade Runner 2049, Jared Leto's Wallace goes to presumably painstaking effort to recreate the replicant Rachael--to the best of his abilities, at least. The process of recreating Sean Young's appearance in the film, director Denis Villeneuve told GameSpot, was just as intense.

They started by casting a lookalike actress with the same height, skin tone, and general appearance as Sean Young in the original Blade Runner. Then they brought in Young herself, who's fully credited as an actress in the film, to coach the lookalike on exactly how to move. Rachael's elegant gait is pretty distinctive, after all, and it had to look believable when she walked in the room.

Once it was all shot, Villeneuve handed it to a VFX company that worked full time for an entire year to make Rachael look like Rachael. The director said he was especially worried about this process thanks to some other recent examples that looked less than stellar, including Carrie Fisher's Princess Leia and Peter Cushing's Tarkin being recreated in the Star Wars movie Rogue One.

"When we were doing the process I saw Rogue One, and I went back to the editing room, and I said guys--I didn't like it at all," Villeneuve said. "I have a lot of respect for that director, and that movie I thought was great, but it took me out of the movie." Villeneuve told the VFX artists that if the director's mother didn't buy it, it wasn't good enough.

"I want my mother to say, 'Oh, you found someone who looks really like her!'" he said. "I didn't want people to think it's a synthetic performance."

What about Sean Young's voice? How did they get Blade Runner 2049's new Rachael to sound like the classic?

"Sean's voice is different, very different," Villeneuve said. "So we put samples from the first movie, where the character is in the same kind of emotion, then we worked with several actresses in order to find the closest thing that sounds like Sean Young, as close as possible. It was a long process to find the right one."

The computer-generated Sean Young that appears in Blade Runner 2049 may be the best example yet of CGI being used to resurrected deceased or aged actors for new roles. It will likely be viewed as a high-water mark for future attempts. But Villeneuve thinks we're still far away from this becoming common practice. He said the problem with Rogue One's CGI characters might have been simply a lack of time on the filmmakers' parts.

"It [takes] very long to do. That's the thing that maybe saved my ass--is that I limited the amount of shots [with CGI Sean Young in them]," Villeneuve said. "It's tough to find the unique computer artists that will have the sensibility of a director. I was talking to them like I direct an actor. My VFX supervisor, they were like a pit bull. They didn't let it go. They worked seven days a week for months, pushing, pushing, pushing."

"If I was a SAG [Screen Actors Guild] member I would not worry, because it's so difficult," he continued. In other words, real actors shouldn't worry about being replaced by CGI any time soon.

Fortunately the effect in Blade Runner 2049 is far less uncanny valley than in Rogue One. Villeneuve, too, is happy with the results.

"For me it's mesmerizing," he said. "You see her coming, and Deckard's looking at her, and I want myself to believe. We did it. We worked on it until we felt that she looks real, that I was emotionally involved like the other characters."

Check out GameSpot's Blade Runner 2049 review, and don't miss Blade Runner Blackout 2022, the anime short film that bridges the story between 2049 and the original. Speaking of the original, if you've never seen it, here's a breakdown on exactly which version of the original Blade Runner to watch.