This article was originally published on June 6, 2025 - read the full issue here

Interview by Nick Evanson, words by Patrick Garratt 

This week, Epic and CD Projekt Red showcased one of 2025 biggest tech demos, headlining Unreal Fest in Orlando, Florida, with The Witcher 4 on the same day Unreal Engine's latest version, 5.6, was made available for open download.

Showcasing new foliage systems, new NPC interactions, hardware ray-tracing and new animation tools now included in Unreal Engine, the demo delivered the goods with what appears to be a blissful marriage of Epic's engine team and Poland's most renowned triple-A developer. REDEngine, the tech used to build The Witcher 3, has been replaced, making the sequel an Unreal Engine project.

"This one was chocolate and peanut butter," says Wyeth Johnson, Epic's senior director of product strategy, talking to us after the keynote. "These were two things that were perfectly aligned."

Johnson adds that building Unreal Engine out to support the largest open-world games has been a longterm goal for the Epic team.

"This is exactly what we wanted to do in Unreal, and have been talking about since the middle of Unreal Engine 4," he says.

"Improving open-world development in Unreal is a very long conversation. You can go back to each and every release and see something in it that is guiding us towards even more excellence in open-world development. [...] We ramped up the ramp dramatically for this release, and I think it shows."

He continues: "Every developer who is trying to do something really originally creative in the triple-A space, they're all going to be excited about this release."

The development effect between the two partners is reciprocal and cyclical, not just the engine-maker adjusting to the needs of the developer. Julius Girbig, senior technical animator at CD Projekt Red, highlights the benefit to the developer's work for all Unreal Engine users.

"The cool thing is that tools that we're building to power Witcher 4 are also now part of the official 5.6 release," he says.

"People can just play with it, but this is also part of us being transparent. [...] We're letting our pants down, essentially. It's like, 'Hey, look at this directly. You can check it out play with it.'"

For example, Smart Objects, the UE plug-in that CD Projekt Red uses as a "baseline framework for handling open-world content", was extended by the developer "using a custom-like proprietary animation system". This type of iteration is actively encouraged by Epic, which adopts a philosophy of adaptation: the team tailors the engine to suit specific requirements.

But the demo's focus was on official release updates related to large environments, such as the creation of large quantities of replicable elements including foliage, and design specificities of large RPGs, such as NPC interaction. UE 5.6's new additions are strongly welcomed by less technically focused developers such as Girbig, an animator.

"I'm a pretty surface-level developer, an animation artist, so I'm not actually digging into code that much," he says. "But I'm still able to run hundreds of characters and create behaviours for them within the editor with a supportive UI. It just unlocks me as an artist.

Unreal Engine's use of Blueprints, a Scratch-style UI in which blocks are laced together to describe actor behaviours, also benefits less technical developers and encourages their creativity within the team environment. While this simplification of the coding process is obviously beneficial for small teams, the benefits across large studios (CD Projekt Red has over 600 staff) are also obvious.

"You can use Blueprints as a sort of visual UI layer of very complex stuff underneath," says Girbig.

He adds: "Just executing C++ code through Blueprints, we're doing that all the time. It's also great for prototyping. You can have tons of iterations very fast. You don't need to compile anything. And then you can tell a programmer, 'I sort of found the thing that I actually want you to build,' so now we're settling on a solution. Then we move it to C++."

For Epic, facilitating large-scale development and focusing on performance has been a key goal for 5.6.

"We need to leave room above the systems we provide so that game designers who maybe aren't programmers can implement and ship them," says Johnson.

"We need to bring the overall level of the engine down and keep the overhead as low as possible so that developers themselves can implement interesting behaviours and they can trust that those behaviours can go right in for players to experience."

Partnership through humility and understanding

The demo on stage in Florida this week marks a significant turning point for Unreal Engine, which aims to be the preferred option for any genre of game.

"We have to approach these relationships with humility," says Johnson. "We have to truly understand that we don't necessarily know better than these people who have a proven track record of delivering amazing things."

The only relevant solution from Epic's side is one of learning.

"We have to approach those conversations with some instinct, some sensibility from what we've done in the past and what we're currently shipping and developing, and then we have to listen."

Increasing Unreal Engine's suitability for open-world development was critical in the partnership between CD Projekt Red and Epic's partnership, Johnson continues: "The dream is that we get to work with smart people and they tell us that where we're headed is correct, and then we have to make changes if it's not."

Ultimately, for a developer like CD Projekt Red to move away from RedEngine, the third iteration of which was used for The Witcher 3, the foundation between the creative and technological aspects has to be solid and unquestionable. Based on what was seen in Florida this week, Epic has managed the partnership expertly.

"Obviously, it was a well-thought-out decision to move over [from RedEngine]," says Girbig. "We looked at a bunch of different engines and really evaluated it. It was a conscious decision that Unreal is the right tool for us, especially when we move to multiple different projects at the same time. It was a great decision, and I think the demo actually shows it was worth it, that the work that we put in is paying off, especially with a great cooperator like Epic. It's been fun, for sure."

This article was originally published on June 6, 2025 - read the full issue here