Decima Engine: New Horizons

The development of Horizon Zero Dawn and the Decima engine on which it runs took place simultaneously; Guerrilla Games’ colourful post- post-apocalyptic adventure takes advantage of tech built specifically to overcome challenges which the Killzone engine would struggle with. The studio’s dark, gritty shooters were contained, linear experiences, but Horizon was always intended to take place in a huge open world.

“At an early stage, we identified the challenges we would meet when creating an open world game, and made a roadmap of tools and tech to ensure that Decima would allow us to fulfill our creative vision,” says Guerrilla Games’ art director Jan-Bart van Beek. “Decima itself is an extension of the engine used for Killzone, so many of the asset creation and rendering techniques from Killzone: Shadow Fall were leveraged and improved upon.

“The more substantial changes to the engine and content creation methods came from the need to create, populate, stream, and render a world many times larger than we were traditionally accustomed to building.

“Decima had to support everything from macro scale landscapes, to large cities and remote villages, to herds of Machines and travelling merchant characters, to individual blades of grass, and everything in-between.”

At the flick of a switch we can turn a dense, palm-filled, and humid jungle to a sparse, dry, cacti-filled desert environment 

Jan-Bart van Beek 

A mixture of procedural and hand crafted design allows the team to create authentic biome-style areas, complete with systems, by utilising what Guerrilla calls World Data. “Decima has allowed us to elegantly construct various natural settings via the development of World Data,” says van Beek. “This is a standardized stack of data and rulesets that are customizable for the various natural settings (or ecotopes) throughout the game world.

“At the flick of a switch we can turn a dense, palm-filled, and humid jungle to a sparse, dry, cacti-filled desert environment. This global system also allows us to simultaneously place pickups and collectibles, wildlife, and even spawn ambient sound effects and environment-specific dialogue.

“We then integrate hand-crafted elements into the broader gamescape to create the unique player experiences required to tell Aloy’s journey. This portion of the effort is most similar to the asset creation we had grown accustomed to while working on the Killzone titles, but sat neatly within the more generative open world elements. Ultimately we end up with a layered tapestry of interrelated assets that can be experienced from different angles and at different times.”

As games continue to become more advanced, the need for specialised skills increases hugely. Art teams are no longer groups of artists who have similar skills, but with differing styles. “It’s getting ever more complicated with every generation of hardware,” says van Beek.

“While 20 years ago a development studio might have an art team of ten people who were all very generalist in their skillsets, the constant push towards larger game- worlds, higher levels of realism, higher resolutions, levels of interactivity and dynamism, etc. has created the need to have larger art teams with highly, highly specialized people.

“Just on making characters there is a structure of maybe 10 different roles, from art directors, concept artists, modelers, texture artists, shader artists, animators, technical animators, facial animators, etc. And that’s just for characters. For machines you’d see that entire structure duplicated with the different artists that specialize their role towards doing all that work for machines.

“Normally, our environment artists tend to be a bit more generalist, but as Horizon was such a new thing, with lots of new things to learn, we also decided to allow these guys to specialize more. So we now have separate artists for landscapes, settlements, trees, rocks, etc.

“All in all the art team of Horizon is probably around 100 people, if we count just the artists who are Guerrilla staff. Next to that, there are probably another 100 or so working for us as freelancers or at various different vendors around the world.”