Evolving the machine creatures of Horizon Forbidden West

Horizon Forbidden West, Guerrilla Games' humongous sequel to Horizon Zero Dawn, goes bigger and bolder with the machine encounters that define the series. Across deserts, mountains, and coastlines, player character Aloy goes toe-to-toe with massive machines sculpted to resemble real-world animals. 

Combat against these creatures isn't a straightforward affair, and players need to adjust tactics whether they're fighting a Burrower, Tremortusk, Thunderjaw, and more. 

Some machines are new to Horizon Forbidden West, some made their first appearances in Zero Dawn. But all of them needed to go above and beyond what Guerrilla had built for its previous game, both to keep players on their toes and showcase what was possible on the PlayStation 5 showcase sequel. 

Guerrilla Games Dennis Zopfi, lead combat designer Dennis Zopfi and lead asset artist Maxim Fleury were down to chat about key updates the team made to Horizon Forbidden West's incredible machines, detailing what tricks they used to make sure the robots were functional, and identifying what core mechanics they wanted to update this go-around. 

Mechanical magic

Zopfi kicked off our chat by breaking down Guerrilla's key goals for the machines of Horizon Forbidden West. For returning machines, he explained that the studio wanted to avoid overlap on some machine designs while iterating on existing enemies.

For instance, he called out that the "Watcher" machines from the first game (scouting entities that warn other machines about player movement) was re-designed as the "Burrower," a small, ferret-like machine that shares many of the Watcher's core mechanics, but also tunnels underground. 

"It was important to keep the new machines fresh and exciting while not making the recurring machines obsolete," he explained. New machines also had to feel like they naturally existed in the world of Horizon.

All of Forbidden West's new machines were built on the back of two basic design goals: first, they would need to have unique visual movements. Second, they'd need new combat mechanics to "ensure a fresh gameplay experience."

One of the earliest new enemy types players encounter is the Leaplasher. In layperson's terms, it's a robotic kangaroo. It likes to leap around and will sometimes lash out at players with a cargo claw that extends out from the body. Among my friends, it's a controversial creature, because its combat patterns can feel less predictable, and it excels at pinning players down for other enemies to kick the snot out of them.

Fleury expressed fondness for the creature, saying it was a "team favorite" before Forbidden West's release (he is entitled to his opinion).

Zopfi said that creating the Leaplashers meant creating a new kind of movement animation—hopping. "Giant (and prehistoric) kangaroos gave us lots of ideas for animation!" He explained that the cargo claw weapon came from iterating on a kangaroo's pouch. Said "pouch" can contain resources, but it became part of the Leaplasher's attacks, whipping it around and deploying it against the player.

A Leaplasher

That attack strategy is also a new behavior type for Forbidden West players who grappled with cargo-carrying enemies from the first game. Creatures like Bellowbacks and Shell-Walkers worked to protect their precious cargo. 

Leaplashers will smack you in the face with it. 

We also quizzed the pair about a major design change to human enemies in the game: this time around, many of them fight alongside machines. Some ride on bull-like Chargers or elephant-esque Tremortusks, others fight in tandem with machines like Frostclaws, which were designed after polar bears.

Zopfi described the process as "technically complex" to make challenging encounters with human enemies. That complexity grew layered as machines were added to the mix, and then human enemies mounted on machines too. "From a design perspective the challenge is always to work in interesting combat approaches or various options for player tactics," he explained. "And that varies a bit with machines and human enemies."

So Zapfi said, these encounters required extra attention on the design team, making sure every enemy encounter that featured both types could still support a different set of tactics. The bad outcome would have been if the clashing combat styles drove players into one strategy with every single fight, in a game that succeeds when players are mixing up tactics all the time.

Asset assembly

Horizon Zero Dawn’s machines were designed—technically and abstractly—for the PlayStation 4. Though Forbidden West also plays well on the PS4, its designers got the chance to re-invent their creatures for the PS5. 

Fleury told us that for returning creatures, Guerrilla was able to re-use models from the first game but overhaul the textures for old machines so they could work with Forbidden West's improvements to the game's textures and engine. 

He said these changes made it much easier to create "Apex" variations of machines—specific enemy types that provide more challenge in combat. 

An Apex Thunderjaw

Originally, Fleury said that Guerrilla built new machines for the sequel by making them be very "in line" with the original game's models and textures. "But as the game progressed and the new machines turned out to be more complex and generally larger than the first game, the models also grew more complicated," he explained.

The goal eventually was to "top" the first game, but the team still had to make sure Forbidden West ran at a decent frame rate. He said that "being very smart" about the way the art team organized the game's textures allowed them to make sure important features would get maximum resolution.

Machines old and new for Forbidden West relied on similar visual logic with some key rules. Fleury said that the base body of all machines is made from darker materials (like carbon, gunmetal, or rubber), and it makes the lighter armor plates on top easier to stand out and aim for.

"Interactive parts then get color coded, either on the part itself or as a decal on the plate covering it," he said. "Yellow stands for resources and orange designates parts like weapons or weak points."

On the design side, Zopfi pointed out that "important" machine parts can easily catch the player's eye, but some hard-to-get parts were still deliberately tucked away to enhance the challenge and add difficulty to fights. Machines like the Widemaw (a big mechanical hippo) have key resources hidden that can only be obtained by using stealth, the Ropecaster (which ties machines down), or elemental damage.

The Widemaw is actually a great example of this design strategy. Its most valuable resources are a set of massive teeth that only appear either by blasting armor off the machine's mouth, or shooting into the mouth while it tries to eat the player. Choosing to go after this particular part is an exercise in adapting to Horizon Forbidden West's varied weapons and mechanics, and players may still win the fight without getting the object they want. 

Now, which machines did Zopfi and Fleury love the most? Zopfi pointed to the Shellsnapper and Slaughterspine, and explained he was big fans of them being "atomic breath" creatures.

But Fleury said he fell in love with the Tremortusk, that its concept "spoke to [him] from the beginning." "Who wouldn’t want to build a hulking mammoth robot with 4 tusks and a warhut on top," he quipped.

Who indeed? If Sony rolls any of these out in the real world...now we know who to thank.