How Eternal Strands' complex chaos was made possible

For developers in the triple-A space, chasing high-fidelity photorealism is often the norm as a way to immerse players into believable worlds. The most impressive aspects of Unreal Engine 5 has also been how it's able to push photorealism to new heights that's also made more accessible with MetaHumans or its huge Quixel library of 3D-scanned environments. Yet while Yellow Brick Games is founded by Ubisoft veterans, including game director Frederic St. Laurent and CTO Louis Tremblay, for new action RPG Eternal Strands, the decision was made early on to pursue a more stylised aesthetic that also serves the gameplay.

As a fantasy game where you play as Brynn, a weaver who is able to use magic, these aren't just spells that involve shooting elemental projectiles. Instead, the laws of thermodynamics are applied, so fire burns and spreads while even forming ice around a dragon's foot can stop it from flying.

"Because we knew from the first week that we wanted something akin to the thermodynamic system that we have, this requires dramatic change visually to be understandable by the player," Tremblay explains. "So having something that is more stylised lets us say that a hot rock is red, or something that is really cold is blue, which, in reality, makes no sense."

The fantasy setting was similarly suitable based on the kind of materials players would be interacting with. "It's easy for the player to understand the physical properties of rock and wood," Tremblay continues. "You can make rock brittle because it's seen so many times in movies, as opposed to different alloys, which makes no real sense, and you need to look at the stats to understand."

Going hand in hand with that was also a desire to make environments destructible, which might cast back to PS2-era games like Red Faction. That such an immediate example is also a game from over two decades ago also speaks to how rare or difficult such a gameplay feature is when considering the many worlds you traverse in modern games often amount to super detailed set dressing.

"We wanted to destroy trees and walls, but if you go realistic, a tree has a lot of splinters when it starts to break, and it's harder to do," St. Laurent says. "We manage to have a full wooden house that is destroyed by a dragon walking into it, which just explodes into planks, and the style kind of allows it. When I worked at a triple-A studio, the house would not be breakable because making it interactable like a game should be is too costly."

Trembaly adds, "We had the philosophy of never saying no because we cannot provide a realisation of something. It's always gameplay first."

Using Unreal Engine 5 for Eternal Strands

While coming from Ubisoft's proprietary tech meant Unreal Engine has been new for St. Laurent and Tremblay, who also began development of Eternal Strands in Unreal Engine 4 before making the upgrade to Epic's latest engine, it has nonetheless granted many benefits, not least the time and cost required to build your own engine.

"Having access to the source code of Unreal has been a boon for us, because it lets us modify the engine, which is something that is more complex to do with Unity, because you have to pay for it," Tremblay explains. "The biggest benefit is that we can hire people that understand [Unreal] simply because it's public. So the pool of people available is a lot higher. It's a lot easier to step up, as opposed to a proprietary engine that nobody on the team knows and that you don't have access to a lot of documentation online, or none at all."

Although some of the most impressive demonstrations of Unreal Engine 5's tech has been with the most high-fidelity and realistic visuals, its unique tools have still proven very efficient, such as Nanite's virtualised geometry system. "Nanite is a cheap way of generating geometry that does not have a higher or lower resolution mode based on distance, which also removes the pop-in you see in games when you change resolution," Tremblay continues. "Even if our models are not hyper-detailed, it still lets us keep very consistent and reduces the manpower needed to optimise the game."

Lumen's dynamic global illumination system has also been used very effectively while reducing the manpower of traditional lighting methods. While both come at higher GPU cost, the trade-off has not had the same issue with other recent Unreal 5 releases that have suffered performance-wise on console. "We are not hyper realistic, so we can control that GPU cost."

Given the heavily physics-based gameplay in Eternal Strands, notably the ability to use telekinetic powers like grabbing and hurling large objects or enemies in the air, Unreal 5's Chaos physics and destruction system has also been vital. This nonetheless required transitioning from PhysX used in Unreal Engine 4, which Tremblay says hasn't been without issues due to Chaos being a newer system. "PhysX was a very mature project, while Epic is still heavily optimising Chaos. But because we have access to the source code, it lets us dig deeper to understand problems than we could have with PhysX."

Designing Eternal Strands like an accordion

But while Unreal Engine 5 does allow for smaller teams to realise ambitious projects, being able to do that in a timely and cost-efficient manner is ultimately down to how that vision is realised, which comes from being able to make smart game design decisions early on.

"One thing I made sure of early on with several people on the team was trying to make a design that is like an accordion," says St. Laurent. "That is like a module, so you can plug in and play or not have something without everything crumbling. It's not like if you remove one giant boss you just come into an empty arena."

He also talks about how he worked with creative director Mike Laidlaw in creating the world logic and lore. Because while Eternal Strands is set in quite a specific area called the Enclave that's cut off from the rest of the world, it was still important to imagine everything else around it. "We started drawing maps, thinking, how many factions or nations do we need to make a world, because even though you don't go to those locales, a world needs to exist if we wanted the Enclave to be credible If you engage in the codexes scattered in the environment, you will probably learn a little bit more of that."

The Enclave nonetheless has an impressive sense of scale, from tall buildings you can climb (not to mention the 25-metre giant enemies you can also climb up to fight) to secret cavernous laboratories deep underground. Crucially however, the team avoided making it an open world to reduce extra work, and instead created loomgates, an in-game travel system to reach different parts of the Enclave, but which also made it easier to make each map distinct with its own biome or features.

"We wanted an Enclave that has a lot of variety of biomes, because we want to see different things on the grounds for us," St. Laurent explains. "The notion about technological marvels was that while there's a fantasy feel, the more you dig into the Enclave, the more you would discover locales that's a bit more sci-fi. We also didn't want you spending 30 hours in a forest."

The artists and level designers' hard work in building the different parts of the Enclave aren't discarded one-offs either as the loop requires you to revisit areas. But as part of that modulated accordion design, other elements such as a weather system, day and night states, and rotating enemy placements also means the same map can be experienced differently multiple times, not just visually but also in gameplay.

Its stylised aesthetic has also given Yellow Brick the flexibility to employ different art styles too. So while there are occasional in-engine cutscenes, more complex story sequences feature anime-style cutscenes, which were made by fellow Canadian animation studio Du Coup, while dialogue with companions use hand-drawn portrait art.

"It was very pleasing to allow ourselves to explore different art styles within the same art direction," says St. Laurent. "Each of these mediums brings their own thing. For example, if you're trying to get the full fidelity of conveying emotion in dialogue, if you're off, you can get into the uncanny valley. With portraits, you let the player imagine the real emotion behind it."

In other words, Eternal Strands makes shrewd use of Unreal Engine 5 by, not pushing for photorealistic perfection in favour of stylisation that complements its ambitious gameplay ideas, while smart design decisions allows that vision to be stretched in imaginative ways manageable for the studio's mid-size team of around 60 people. Yellow Brick Games may not have the big budgets of triple-A but it can still make magic happen.

Eternal Strands is on sale now for PS5, Xbox Series X and Steam, visit the Yellow Brick Games website for more information. Inspired? Then read our guide to the best game development software and start creating.