When Elias Toufexis (“The Expanse,” “Supernatural”) got called in to audition for Ubisoft’s next big game, his agent knew nothing about the role or even what the project might be. Video games are a clandestine business. “My sides — the lines they gave me for the audition — were from ‘The Godfather,’” Toufexis recalls. “It just said, ‘Do this, but in a Greek accent.’” Nevertheless, he was asked to sign a non-disclosure agreement. “Even if you wanted to talk about it, you would have no idea what the hell you were talking about,” he says with a laugh. “All I would have known is that Ubisoft is making a game with Greek accents.”

As it happens, Toufexis had grown up listening to his Greek grandparents tell stories, so he nailed the voice, and was cast in not one but two roles in Ubisoft Quebec’s upcoming “Assassin’s Creed Odyssey.” (“It’s kind of my tribute to them,” he says.) One of the roles is that of Leonidas, the king of Sparta; the second, naturally, is being kept secret.

“They don’t tell us that much,” Toufexis says. “They give us the script that we have, and they say, ‘These are your scenes.’ And I say, ‘What else is going on?’ They’re like, ‘Well, we’re not going to tell you that.’ So I don’t know where they’re going with the mythology of it, but personally, if I get to fight Medusa or Cerberus or something, I’ll be really happy.”

While most details of the game’s story are still under wraps, it begins at the famed Battle of Thermopylae, with Leonidas expressing regret for never having taken his child fishing. After a few quiet moments, he readies his men for war. “The Persians come to make slaves of us all,” says Leonidas. “I have a better idea: I say we drench the gods with their blood!” Under the helmet, the character resembles Toufexis, albeit with long hair, a large beard, and digital flourishes that make him appear decades older than he is. “I still see me,” Toufexis says.

Like certain specialized film and TV roles, the most famous example being Andy Serkis’s Caesar in the recent “Planet of the Apes” trilogy, many video-game parts utilize full-body performance capture. “The technology evolves literally every time I go on stage,” Toufexis says. “Whether it’s the amount of dots they put on my face, or whether the suit is a little different. There’s a helmet they put on your head that has a little lightweight camera that points directly at your face, so they capture your face, and that gets lighter and lighter, and more and more comfortable.”

Generally speaking, this results in the actor being represented by a computer-generated model in the final image. It also allows for an actor’s entire on-stage performance to be recorded in three dimensions, giving animators the option to draw footage from any conceivable angle, and even make changes as needed.

Michelle Boback

“The animators do a lot of work on you,” Toufexis says. “They’ll eliminate a fleeting glance, or they’ll add like a smirk or something like that, if they feel like the scene would work better that way. But for the most part — I would say 90 percent of it — whatever the actor did is just mapped onto the grid, and then they animate over that.” He likens the process to the use of makeup and prosthetics, arguing that it’s at least as expressive as John Hurt’s role in 1980’s “The Elephant Man,” which received Oscar nominations for best actor and best film despite its star being unrecognizable.

For “Assassin’s Creed Odyssey,” the art of performance capture was made all the more complicated due to the game’s foundation of choice. “Odyssey” offers branching dialogue, decision-making, and multiple endings, but it also gives players two distinct protagonists to choose from: a woman named Kassandra (Melissanthi Mahut) and a man named Alexios (Michael Antonakos).

“Because there were two main characters, every scene had to be done twice,” Toufexis explains. “You couldn’t do one scene with Michael for Alexios, and then go do something else — and make a different choice as an actor — for Kassandra. Because that would just betray the whole point of the game.” So every non-lead actor on the project would have to carefully review their performance, and then try to match it exactly while reacting to the real-time performances of the two stars.

“The way I would speak some lines to a man are different than the way I would speak some lines to a woman,” Toufexis says. “But they were the same lines, and every actor who worked in the scenes with them had to figure out a way to say the same lines, with the same intention — but they’re gonna always be different depending on whether you’re talking to a man or a woman. So it was a really big challenge. I’m gonna have to play the game twice, because I’ll want to make sure that our scenes gelled.”

Another hurdle he faced while giving the performance was in differentiating it from Gerard Butler’s famous turn in the movie “300.” “Whether we like it or not, the dialogue is gonna be pretty much the same,” says Toufexis. “That thing is popular because of ‘Come and get them,’ and ‘This is Sparta.’ And those are the things that we think Leonidas actually said.” Toufexis did some research into the real-world history behind the figure to prepare for the part and make it his own, he says. But at the end of the day, it’s a video game, and fun is the prime directive.

Looking back on the last decade of his career, he’s amazed by how far the medium has come, in terms of both dramatic potential and methodology. He recalls going out for the part of the villain in “Rainbow Six: Vegas 2,” and doing the audition in a sound booth; these days, that process is just like television. And with every project, a day on stage for game feels a little closer to a day on set for a movie or TV gig. “Slowly, as things moved along, they started treating it more like a film set. They’d get ADs and things like that, and they would give you set schedules. And so now going to work is so much fun.”

Toufexis has acted in more than two dozen video games over the years, but none has required the amount of forethought needed for Leonidas and his other mystery role in Ubisoft’s “Odyssey.” “There’s gotta be a hundred characters in that game,” he says. “I can’t imagine the amount of work that’s gone into it, to do two protagonists. It’s a really gutsy thing to do. I hope it pays off.”