The Callisto Protocol looks so lifelike, even the eyeballs are ray-traced

The face of Jacob Lee in The Callisto Protocol
(Image credit: Striking Distance Studios)

Striking Distance Studios wants The Callisto Protocol to look so realistic that even its characters’ eyeballs will root you in the game’s body horror.

Speaking to TechRadar Gaming at Gamescom 2022, chief technical officer Mark James said The Callisto Protocol has been developed with maximum realism in mind. The team made it a priority to create the most convincing characters possible by trying to render them at an unparalleled level of detail.

“Our characters are the most realistic characters you'll see in a game,” says James. “So much so, that when we first showed our game, everybody thought it was pre-rendered. We were like, 'No, this is how our character looks. This is how Josh [Duhamel, the actor behind the game’s main character] looks'.

“We've got a full scan, even down to ray-traced reflections for the eyeballs. So if you look into the [character’s] eyes in our game, you can see their reflected optics. It’s a really tiny detail, but it's those tiny details that actually are so important to our game.”

Go for the eyes

Jacob Lee in The Callisto Protocol firing a gun at a two-headed human mutant

(Image credit: Striking Distance Studios)

To create such precise optical details, the team meticulously modeled light reflections at every angle. By rotating lights around the game's character models, they could accurately recreate those bounce properties in the character’s eyes, even accounting for changes in direction and type of light source.

“Our rendering guy, Jorge Jiminez, used to send round photos of Josh and the digital render [of the game's main character], and he would get people to guess [which was which]. If people thought there was any difference, he then worked on that area. It's so important to us that that realism is in our game.”

Painstakingly rendering character eyeballs served a greater purpose than just supporting the graphical fidelity of each character. James reckons creating convincing faces is essential to selling the realism of The Callisto Protocol’s wider world.

“It brings a connection to the player that you don't normally get,” he said. “So much of our brain is associated with seeing faces, more than the rest of the world around us because we have to read faces every day. 

“If realism doesn't exist in the faces, then you start to not believe the realism in the rest of the world. We really wanted to concentrate on where you spend the most brain power in assessing an image.”

The Callisto Protocol

(Image credit: Striking Distance Studios)

Convincing character faces are also key to underpinning the horror that sits at the heart of The Callisto Protocol. Each enemy in the game is a grotesque mutated human, and James says that players must recognize that – see the remnants of humanity that exist within them – to truly fear them. 

“You can still see a face in our enemies,” he said. “You can still see that they're disjointed; mutated in a way that's natural.” 

“We want to base all of our mutations and our body horror around this grounded reality – what would happen if an arm grew twice the size, or a chest opened up.

“Our enemies aren't the undead, they aren't aliens, they're mutated humans. So we want to show that grounding – they're still recognizable as humans – and also that connection, so you're not just dispensing with these things that used to be human. They’re your fellow prisoners and guards.”

The Callisto Protocol is set to release on December 2. It’ll be coming to PS5, PS4, Xbox Series X|S, Xbox One and PC.

Callum Bains
Gaming News Writer

Callum is TechRadar Gaming’s News Writer. You’ll find him whipping up stories about all the latest happenings in the gaming world, as well as penning the odd feature and review. Before coming to TechRadar, he wrote freelance for various sites, including Clash, The Telegraph, and, and worked as a Staff Writer at Wargamer. Strategy games and RPGs are his bread and butter, but he’ll eat anything that spins a captivating narrative. He also loves tabletop games, and will happily chew your ear off about TTRPGs and board games. 

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