Image courtesy of Sony Interactive Entertainment, Guerrilla, and Firesprite

How Horizon Call of the Mountain leverages PS VR2 to deliver next-gen virtual reality

Jimmy Thang
Jan-Bart van Beek is one of Guerrilla’s Studio Directors as well as Studio Art Director who has been with the studio for over 21 years. In his role as Studio Director, Jan-Bart focuses on daily operations, business development, multi-project management, and employee well-being. As Studio Art Director, he is responsible for developing, coordinating, and implementing the visual style for all Guerrilla and franchise projects. Jan-Bart and the art teams are currently focusing on Horizon Call of the Mountain and Horizon Forbidden West: Burning Shores.
Developed by Guerrilla and Firesprite, Horizon Call of the Mountain is the next installment in the critically-praised and beloved Horizon franchise. It is one of PlayStation®VR2’s marquee launch titles. In the game, you play as disgraced soldier Ryas seeking redemption in a standalone title set during the events of Horizon Zero Dawn. Developed using Unreal Engine, Horizon Call of the Mountain offers gorgeous visuals and vibrant colors that take advantage of PS VR2’s next-generation virtual reality platform.

To learn more about the development of the game, we interviewed Guerrilla Studio and Art Director Jan-Bart van Beek, who talks about some of the goals coming into the game’s development, how the team iterated on Horizon Call of the Mountain’s gameplay loop, how they approached combat design, and more.

For the uninitiated, what is Horizon Call of the Mountain about?

Guerrilla Studio and Art Director Jan-Bart van Beek:
Horizon Call of the Mountain is a PlayStation VR2 game developed by Guerrilla and Firesprite. It tells the story of Ryas, a disgraced former Carja Soldier. Players see the world through his eyes while he seeks redemption for his past actions.

Where does Horizon Call of the Mountain fit within the previous two games in the series?

Horizon Call of the Mountain takes place between two missions in Horizon Zero Dawn, although it is not necessary to have played Horizon Zero Dawn to understand Horizon Call of the Mountain. We are excited to see if our players can pinpoint what missions these are!

With Horizon Call of the Mountain being the first VR entry in the esteemed franchise, can you talk about some of the goals you had coming into the project? What advantages does VR bring to the world of Horizon?

This is a unique, new Horizon experience, one that has been built from the ground up for PlayStation's next-gen VR hardware. The world around you feels alive and immersive, from the rumbling of a huge machine stepping over you to the tension of pulling a bowstring. VR truly offers players that authentic experience of being in charge and experiencing the game world on a whole other level, and we put great care into every detail to make sure that this is how it comes across.

Exploring the world in first-person is a spectacle. The team really made the world feel majestic, with potential danger lurking around each corner. Taking on the ferocious machines will have players calling on every skill they’ve learned throughout their playthrough! We look forward to seeing how our community faces the challenges of the wilds.
With exploring, climbing, shooting, a river ride mode, and more, Horizon Call of the Mountain features a robust gameplay loop. Can you talk about how the team iterated here?

With Call of the Mountain, we gave ourselves the challenge to make a game that would be a great gaming experience both for newcomers to VR as well as veterans. VR tends to be an intense gaming experience. It’s much more physics than traditional gaming, and the level of immersiveness is unmatchable by a flat-screen TV. It’s easy to overestimate how much players can handle and overwhelm them.

The way to iterate was to playtest extensively and really look at the players while they were playing. Aspects like body language and even breathing patterns start telling you a lot about how people are reacting to the game. It’s a very different way of designing games.

Were there any unique challenges the team had to overcome to ensure the Horizon universe fit well in VR? If so, how did you solve them?

We always believed that the world of Horizon would be great to experience in VR, and while getting all its majestic natural landscapes and its awesome machines to run efficiently in VR was certainly challenging, it was not the biggest challenge. In VR, immersion is often almost perfect, and it tricks your brain into believing the world around you is real. But we also provide the player with two hands, and that gives them the promise that they can use them as if they are real hands. That was our biggest challenge, not just delivering the world of Horizon in virtual reality but also giving players a satisfying level of fun interaction with that world through their own hands.
Image courtesy of Sony Interactive Entertainment, Guerrilla, and Firesprite
Horizon Call of the Mountain is purported to offer multiple paths for players. Can you talk about how you constructed the game's world?

In order to deliver the best possible gaming experience in VR for a wide group of players, we felt it was better to go for a more classic linear narrative structure. But this isn’t a short “tech demo” like experience, but a great full-on campaign-style game experience. And that means we needed to make it meaningful for players that want to replay the game and explore areas they may have missed the first time. To support this, we added some branching paths to certain parts of the campaign, as well as discoverable content that add additional depth to the world.
Image courtesy of Sony Interactive Entertainment, Guerrilla, and Firesprite
Can you elaborate on how you handled combat mechanics in the game?

We quickly found that fully navigating a combat space while large machines are trying to squash the player is a lot to handle cognitively for both new and veteran VR players. So we pioneered a novel combat system that works similarly to a lock-on system. It gives the player freedom to position themselves in relation to their enemy but without the need to keep realigning their rotation as they move around the combat area. We feel it allows a much higher speed in the combat than players are usually able to handle in VR. It allows for a highly dynamic and hectic style of combat while providing a lot of player control.

Considering the game was developed by both Guerrilla and Firesprite, can you elaborate on how that relationship worked?

Guerrilla and Firesprite have co-developed this title, which has resulted in an incredible collaboration between both PlayStation studios. We couldn’t be more thrilled to work together with so much talent!

Can you share how Horizon Call of the Mountain takes advantage of PlayStation VR2?

It was great to be able to leverage the new PS VR2 hardware and all the advantages it brings with it. One example is the use of haptics and triggers for world immersion. Things like tension on your bowstring, different climbing holds, zip lines, plants, and objects in the world all use haptics and the adaptive triggers to give you that extra layer of feedback; for example, when climbing, you will feel the resistance of the handholds.
Image courtesy of Sony Interactive Entertainment, Guerrilla, and Firesprite
Horizon Call of the Mountain is also one of the first games to take advantage of gaze tracking. Can you elaborate on how the team leveraged it?

Yes, we do; in combination with foveated rendering, this allows for a high-fidelity picture while optimizing it specifically to enhance where the players look. Additionally, we are using dynamic resolution scaling to maintain a smooth framerate.

Considering PlayStation VR2's sharp resolution, can you share how the team optimized Horizon Call of the Mountain for VR?

The combination of eye-tracking and foveated rendering is a game-changer. It allows us to render additional detail exactly where it is needed. This allows us to rebalance the power of the PS5 to areas that are critical while lowering the cost of rendering in areas where your eyes are not able to register high levels of detail.

Thanks for your time. Where can people learn more about Horizon Call of the Mountain?

You can learn more at or follow Guerrilla and Firesprite channels on social media.

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