Origins and visual design

The initial concept for the machines in Horizon Zero Dawn (2017) drew heavily from the militaristic and industrial aesthetic of Guerrilla Games' previous franchise, Killzone . However, this direction was abandoned after playtesters reported feeling more like traditional soldiers than tribal hunters; these early designs were instead repurposed as the game's ancient "Old World" machines. ^[5] The core design philosophy shifted to focus on "juxtaposition": placing primitive humanity against highly advanced, futuristic technology to create a world where humans are no longer the dominant species. ^[6] When establishing the visual language of the newer terraforming machines, the team aimed for an animalistic aesthetic. Early on, they experimented with how closely the machines should mimic real-life fauna, but direct comparisons were scrapped for looking unnatural. To avoid predictability, the team combined features of multiple creatures to keep their exact inspirations vague. ^[7] However, several machines were heavily inspired by recognisable animals so their behaviours could be easily understood by the player; for instance, Tallnecks were inspired by giraffes, Stalkers by maned wolves, Longlegs by terror birds, and Watchers by meerkats and small bipedal dinosaurs. ^[3] The look of a machine was designed to tell the player its function immediately; the Watcher, for example, was designed to resemble a security camera. ^{[8] [9]}

When expanding the mechanical ecosystem for Horizon Forbidden West (2022), the designers focused on filling specific ecological niches within the new environments. For example, the Sunwing was introduced to fulfil the need for a flying machine larger than the returning Glinthawk. By studying primitive birds and flying reptiles, the team designed the Sunwing with photovoltaic wings that collect solar energy. ^[8] For Forbidden West's expansion, Burning Shores , the team introduced the pelican-inspired Waterwing, which was designed to fundamentally change player traversal by adding a seamless transition between high-altitude flying and deep-sea diving. ^[10] Guerrilla used visual design to distinguish the distinct origins of the machines in the game's lore. While the newer terraforming machines were based mostly on vertebrates, the Old World Chariot line was intentionally designed with an invertebrate aesthetic, drawing from insects, arachnids, and crustaceans to emphasise their original purpose as hostile weapons. ^[3] The colossal Horus units were designed specifically to visually demonstrate the apocalyptic destruction of the Old World, using a giant, insectoid design that allowed the machines to drape dynamically across the environment. ^[11]

Anatomy and technical prototyping

Seeking a realistic foundation for robotic anatomy, the developers consulted the robotics department of the Delft University of Technology. Engineers advised against traditional internal skeletons, which are common points of failure in nature. Instead, they suggested an exoskeleton approach similar to that of lobsters. This advice shaped the definitive anatomy of the machines: a sturdy, external metal framework protecting softer, internal "tissue" (components). Functionally, this anatomical choice improved visual durability and provided logical, internal "soft spots" that the player could expose and exploit. ^[12] Artists used ZBrush to sculpt high-detail components like hydraulic joints and armour plates, designing the machines as if they could be physically constructed in reality. ^[13]

The game's overarching mechanics were established through technical prototypes. An early machine dubbed the "Predator" appeared as a holographic Easter egg in Killzone Shadow Fall (2013), with many of its behaviour routines eventually adapted for the Sawtooth. ^[14] Early tests with a scorpion concept revealed gameplay issues because its thin limbs lacked sufficient surface area for the player to hit, further solidifying the need for larger machines with modular parts. The true proof of concept was the Tyrannosaurus rex-inspired Thunderjaw. ^[7] It took the development team 18 months to bring the Thunderjaw from an initial sketch to a functional in-game state. To test scale and movement, the very first in-engine iteration was constructed using blocky, "Duplo"-like 3D models with basic animations. ^[6] By successfully implementing destructible armour plating and testing fundamental interactions, such as shooting off weapons or triggering behaviours by striking weak points, the developers learned how to make the core gameplay work. ^[12] These systems were then scaled down and integrated into smaller machines to ensure combat remained readable. ^[5] To further aid this readability, the developers intentionally avoided overloading the machines with blinking lights and colours during combat so the player could easily identify their status. ^[12] The original Thunderjaw prototype eventually brought the franchise's development full circle with the release of the spin-off Lego Horizon Adventures (2024), which visually reimagined Zero Dawn using Lego bricks. To ensure authenticity, every machine in the game was built brick-by-brick by "master builders" following the strict rules of physical Lego, meaning the digital machines could technically be assembled in real life. ^[15]

Animation and audio design

To animate and telegraph the machines realistically, the development team took courses in animal and creature animation and consulted Dr. Stuart Sumida, an anatomical consultant for film and theme parks. ^[12] Lead animator Richard Oud noted that the team frequently used viral videos of bizarre animal behaviour to inspire unique attack patterns. For example, the Bellowback's fluid-flinging attack was inspired by a real-world fight between an emu and a kangaroo; animators noticed the emu curled its neck like a baseball pitcher winding up a throw, which fit the machine perfectly. The burrowing Rockbreaker's movements were based on footage of sea lions fighting to portray a mix of heaviness and agility, while the bear-like Frostclaw's distinct tumbling attacks were inspired by the feisty rolling of red pandas. ^[16] Animation was deeply tied to machine status; for example, the Hermit crab-like Shellwalker has 150 unique animations, and its behaviour changes based on its components. If the player shoots off its cargo clamp, it will use its claw to manually hold onto its crate, sacrificing a weapon to save its resource. ^[17]

While Horus units appear as dormant landmarks in Zero Dawn and Forbidden West, a fully operational unit was developed to serve as the final boss encounter in Burning Shores. The animation team had to navigate massive technical complexity, as the Horus features over 1,240 articulation joints, which was a massive increase compared to the base game's most complex machine, the Slitherfang, which capped at 240. To reflect its nature as an ancient weapon reanimated by an external force, its movements were themed around a "shambling zombie"; instead of powering through smoothly, it was animated to lurch, struggle, and claw its way forward uncoordinatedly. ^[11]

Sound designers balanced robotic and animalistic noises to create an "emotional impact", an approach the audio team dubbed "natural-fiction". ^[18] To ensure the machines felt grounded in reality, the audio team avoided relying exclusively on synthetic noises, instead anchoring the digital samples by layering them with organic, real-world animal recordings. ^[19] By dynamically blending synthetic, electronic creaks with these organic vocalisations, they gave most machines between 200 and 300 unique sounds, with another 150 shared across types. ^[17] To guide these vocalisations, the designers anthropomorphised the machines with distinct personalities; for example, the Shell-Walker's audio was designed to mimic a "grumpy crab-guy" annoyed by his work, while the Watcher was modelled after a "crazy Chihuahua". ^[18] However, rather than simply pitch-shifting the recordings to fit these personalities, the team sometimes analysed the acoustic data of a real animal's call, such as its pitch modulation, and applied that data to recreate the exact auditory pattern with entirely synthetic sources. ^[17]

The team used audio to further distinguish the origins of the different machine classes. When designing the futuristic terraforming machines, sound designer Pinar Temiz intentionally avoided using traditional metal scraping noises because listening to them caused her physical discomfort. She used the lore of exotic, futuristic alloys to justify this limitation, resulting in a unique sonic profile that relied heavily on animalistic cues. ^[18] To ground the machines in the world, the audio team created unique Foley for machines walking across different terrains to convey their weight. ^[17] The underground environments that manufacture the machines, known as Cauldrons, were similarly designed to contrast the natural world. Because humans had never set foot in them, their audio was engineered to sound like loud, early Industrial Revolution factories lacking acoustic protection, mixed with slick, alien synthesisers. ^[19] Conversely, the ancient Old World military machines lack vocalisations entirely, instead relying on heavy, traditional metallic clanks to communicate that they were built using older, recognisable human technology. ^[18]

To ensure the hundreds of unique sounds did not overwhelm the player, Principal Sound Designer Anton Woldhek and programmer Andreas Varga built a highly flexible, systemic audio engine called Guerrilla Dynamic Audio (GuDA). Rather than using hard-coded audio triggers, the engine actively monitors the environment and dynamically mixes the machine sounds, weather effects, and the musical score so they do not overlap and clash. This system actively reacts to variables such as the player's current biome, the number of enemies present, and the shifting "emotional" states of the machines, ^[19] altering a machine's vocalisations dynamically based on whether it is suspicious or aggressive. ^[17] To upgrade the audio for the new machines in Forbidden West, the developers designed highly specific audio cues that allow the player to predict a machine's behaviour, such as distinct sounds for idling, alerting others, or initiating attacks. These details were further amplified by the PlayStation 5's 3D audio capabilities to provide the player with greater situational awareness. ^[8]

Gameplay integration and AI ecosystem

Because the machines are established as caretakers of the Earth, the development team programmed each type to exhibit behaviours that match specific roles within a functioning ecosystem. ^[8] To dictate machine behaviour, the developers used hierarchical task network (HTN) planning, allowing the artificial intelligence (AI) to generate sequences of actions rather than single behaviours. This system enables different machine classes to react dynamically; for instance, Acquisition machines may flee while Combat and Recon machines coordinate to hunt the player. ^[20] To handle navigation, Guerrilla built two distinct systems. Ground-based machines use a navigation mesh (NavMesh) that adapts to complex terrain changes, while flying machines use a completely separate aerial navigation system based on a runtime-generated heightmap. ^[21]

The combat system was designed to facilitate a sense of progression. The ability to shoot off weapons gives the player a temporary "power spike", which is balanced by making these detached weapons heavy and limiting their ammunition. ^[6] The player can also hack or "override" machines using a device attached to Aloy's spear. ^[22] While some overridden machines can be used as ridable mounts, others will only temporarily fight alongside the player. ^[23] The developers chose not to let the player directly control the machines' actions after overriding them, ensuring they remain independent entities within the ecosystem. ^[24] In Forbidden West, this mechanic was slightly expanded, allowing the player to specify whether an overridden machine should take aggressive or defensive stances. ^[25]

As hardware capabilities improved for Forbidden West, the mechanical ecosystem was significantly expanded. Machines gained increased mobility, allowing them to jump, swim, and cling to surfaces. ^[8] The developers also integrated human and machine factions more closely, designing encounters where human enemies actively commandeer machines. ^[26] To increase the challenge, the game introduced "Apex" variants: heavily armoured, deadlier versions of standard machines. ^[27] Developing the virtual reality (VR) spin-off Horizon Call of the Mountain (2023) required Guerrilla and co-developer Firesprite to rethink how the player interacts with the mechanical ecosystem. Guerrilla studio director Jan-Bart van Beek noted that giving the player virtual hands created the expectation of realistic, physical interactions; to achieve this, the team used the PlayStation VR2's adaptive triggers to simulate the tactile tension of a bowstring and the resistance of climbing handholds. ^[28] The developers found that navigating a 3D combat space while fighting massive machines was too cognitively overwhelming for the player in VR. As a solution, they pioneered a lock-on combat system that anchors the player to a circular path around the enemy, allowing for faster and more dynamic dodging without the need for constant manual camera realignment. ^[29]

The franchise's mechanical ecosystem is being further adapted for multiplayer-focused spin-offs. For the upcoming Horizon Steel Frontiers , an MMORPG developed for mobile and Windows, developer NCSoft, in collaboration with Guerrilla, restructured the combat to accommodate large-scale cooperative raids heavily inspired by the Monster Hunter franchise. To translate the tactical depth of the mainline games into an MMO setting, the developers introduced new mechanics, such as the ability to use a grappling hook to climb directly onto damaged machine parts to set traps, and the ability to transport detached heavy weapons using mounts. ^[30] Alternatively, Guerrilla's upcoming PS5 and PC cooperative game, Horizon Hunters Gathering , adapts the machines for roguelite gameplay. Players must coordinate class-based roles to survive "Machine Incursions", wave-based encounters where machines pour out of underground gateways, and navigate "Cauldron Descents", which feature procedurally shifting rooms of machine encounters. ^[31]

Gameplay and encounters

Reviewers have consistently praised the machines as the standout feature of the franchise. ^{[32] [33] [34] [35]} Game Informer 's Jeff Marchiafava stated that the machines "absolutely steal the show" by injecting the world with danger and making combat feel unique, keeping the player constantly engaged alongside the "Pavlovian response" of open-world scavenging tasks. ^[36] IGN 's Lucy O'Brien praised the tactical depth of the combat, noting that the ability to scan the distinct species for weak points and physically shoot off their components fundamentally changes how each fight plays out. She highlighted the ferocity of the machines, which act authentically animalistic and ensure that every major battle maintains a vital sense of danger. ^[37]

Several machine types have been highlighted as standout encounters due to their complex designs and challenging hunting mechanics. ^{[38] [39] [40]} The Thunderjaw is widely considered one of the most iconic and dangerous machines in the game; these fights can turn into lengthy "battles of attrition" where a key strategy involves using precision to detach its powerful disc launcher and turn its own firepower against it. ^{[36] [41] [42] [43]} Other notable combat machines include the Stormbird, a highly mobile aerial threat; the Stalker, which uses optical camouflage to ambush the player; and the Snapmaw, a mechanical crocodile that harvests solar energy and spits super-cooled liquid. ^{[41] [42]} Conversely, the Tallneck was singled out by GamingBolt as a creative, majestic take on the traditional open-world map tower, being the only machine in the game that is entirely peaceful and cannot be harmed. ^[4]

For Forbidden West, critics noted the increased deadliness and smarter AI of the machines, appreciating the introduction of dynamic combat elements, such as machines kicking up dust that the player could use for stealth. ^{[32] [44] [45]} IGN's Simon Cardy praised the sequel's combat, concluding that battles with the larger machines reach a scale and quality that many other games aspire to for their grand finales. ^[46] However, the machine encounters have faced some criticism regarding mechanical bloat and pacing. ^{[47] [48] [49]} Critics noted that Forbidden West occasionally overwhelmed the player with an excess of convoluted weapon variants, overwhelming skill trees, and tedious upgrade grinds. ^{[47] [50] [51] [52]} Furthermore, while the AI upgrades were praised for increasing difficulty, Wesley LeBlanc from Game Informer noted that the machines were highly aggressive, warning that the combat was very challenging and the player could be defeated quickly. ^[53] Combined with punishingly fast damage when Aloy is knocked down, and melee mechanics that remained largely risky or unviable against larger machines-a criticism carried over from Zero Dawn, ^{[38] [54] [55] [56]} GamesRadar+ found that encounters could occasionally devolve from careful, tactical hunts into chaotic battles. ^[33]

The adaptation of the machines in spin-off titles received mixed reactions. Cardy praised the VR title Call of the Mountain for providing a renewed sense of scale and spectacle, turning encounters with previously familiar enemies into "blockbuster scale" experiences. ^[57] However, Eurogamer''s Ian Higton noted that the combat felt somewhat restrictive, as major encounters lock the player onto a circular path around the machines rather than allowing for open-world freedom. ^[58] Reception to the combat in Lego Horizon Adventures was similarly mixed. IGN's Jada Griffin called the combat a "simple but satisfying exercise", noting that detaching specific machine parts successfully altered enemy behaviours during fights. ^[59] Katharine Castle of Eurogamer similarly highlighted the machine encounters as the game's strongest element, praising the blocky redesigns of the recognisable machines and noting that manoeuvring to target weak points gave the fights a "real sense of pep and challenge". ^[60] Conversely, Nintendo World Report felt the translation lacked the precision of the mainline series. They added that the removal of slow-motion aiming made accurately shooting off parts much harder, and that combat could frequently devolve into a chaotic and imprecise experience, particularly when playing in local co-op mode. ^[61]

Visuals and audio

The machines have been praised by critics for their highly detailed visual design and complex animation. ^{[17] [37] [46]} Reviewers highlighted the creative blend of natural, animalistic anatomy with functional industrial components, noting that the mechanized fauna felt like a believable part of the post-apocalyptic ecosystem. ^[b] For Forbidden West, critics praised the massive upgrades to the animation systems, noting how dynamically the machines moved, reacted to their environment, and displayed realistic battle-wear on their armour plating. ^{[46] [50] [63] [64]}

The mechanical ecosystem's sound design was lauded for heightening the franchise's immersion. ^{[36] [46] [65] [35]} Critics praised the dynamic mix of synthetic, electronic creaks with real-world animal vocalisations, noting that the heavy metallic footsteps, screeching metal, and animal-like roars gave the machines a tangible sense of weight. ^{[17] [36] [66]} This auditory immersion was further expanded in Forbidden West, with critics highlighting how the soundtrack brilliantly wove heavy electronic synthesisers into traditional acoustic instruments. ^{[33] [67] [44]} With the release of newer hardware, reviewers also praised the integration of 3D audio and DualSense controller haptics, noting how the controllers physically mirror the movements of the machines, allowing the player to feel the heavy, rumbling footsteps vibrating through their hands. ^{[44] [63] [68] [69]}

Thematic and critical analysis

Jesús Fernández-Caro noted that Zero Dawn blurs the traditional boundaries dividing humans, animals, and machines, placing them all on a shared "continuum of life forms". He identifies Aloy as a "feminine posthuman" whose birth from a machine within a matriarchal society allows her to serve as a bridge between the biological and the technological. Fernández-Caro describes the machines as "postmodern animals" that resist traditional representations of nonhumans as mere tools, instead functioning as a speculative lens to rethink human-animal relations. Furthermore, he emphasises that the narrative uses empathy as the primary key for the player to understand and navigate this ecosystem, ultimately advocating for a mode of coexistence that recognises the value of nonhuman life over human dominance. ^[70]

However, while scholars like Fernández-Caro highlight the narrative's themes of posthumanism and ecofeminism, others have argued that the franchise's gameplay mechanics actively contradict these messages. Andrei Nae and Eirini Bourontzi analyse the mechanical ecosystem as a site of "colonial realism", arguing that the gameplay reinforces colonial and capitalist forms of domination. They point to the "Focus" ^[c] and the in-game map as primary colonial tools; the Focus superimposes a "capitalist colonial gaze" that reduces the machines to their "exchange value", while the map facilitates territorial expansion. Because the RPG economy requires the player to systematically hunt and dismantle machines for loot to fund necessary upgrades, Nae and Bourontzi assert that the player is conditioned to act as a "colonial entrepreneur". Further analysing the machines' origins, they note that the Old World military robots use ancient Egyptian nomenclature, such as the "Scarab", "Khopesh", and "Horus", to define them as antagonists through a Eurocentric moral binary. They also evaluate the franchise against Victor Navarro-Remesal's criteria for a "green video game", concluding that it fails because the machines infinitely respawn and their destroyed chassis eventually vanish without lasting environmental consequence. This design, they argue, promotes a neoliberal ideal of "infinite growth in an infinitely regenerating world", where the mechanical ecosystem is treated merely as a commodity for exploitation rather than a community requiring moral consideration. ^[72]

Conversely, other critics have interpreted the human-machine relationship in a much more positive, symbiotic light. In an analysis published by First Person Scholar, Ian Faith argued that the machines successfully create a "hybrid ecology" where the distinctions between organic and synthetic life, as well as natural selection and artificial selection, become arbitrary. Rather than viewing the hunting of machines as pure capitalist exploitation, Faith wrote that the human tribes practice a healthy symbiosis with the mechanical ecosystem. By using every part of the machine's "carcass" for clothing, weaponry, and cultural items, the games depict a landscape where production and consumption are moderated with very little waste. ^[73] Lauren Woolbright analysed the mechanical ecosystem through the lens of Gaia theory, noting that while the game superficially pits nature against technology, the machines ultimately demonstrate how deeply intertwined the two concepts can be when guided by an environmental ethics of care. ^[74]

Beyond the debate over the franchise's in-game systems, critics have also observed contradictions regarding the franchise's ecological messaging within its real-world production. Scholars such as Alenda Y. Chang have highlighted the "materiality" of the machines, noting a dissonance between the game's environmentalist themes and the massive infrastructure of server farms and hardware required to sustain the mechanical ecosystem's high-resolution textures. ^[75] Furthermore, critics have analysed the creation of the machines as an example of the modern video game industry's reliance on globalised labour. While the overarching designs were conceptualised by Guerrilla in the Netherlands, the intricate 3D modelling of the machines' hydraulic joints, armour plates, and internal components was extensively outsourced to studios in other countries, such as Virtuos in China. The Outline 's Michael Thomsen noted that the immense visual fidelity of the machines is a product of this distributed, outsourced labour pipeline that often obscures individual artistic contributions. Other critics have framed this process as the creation of "asset farms", noting that the machines' animalistic designs were actually the result of highly industrialised and standardised labour practices. ^[13]

Cultural impact and merchandise

The machines' intricate designs have inspired elaborate real-world creations and marketing installations. For E3 2016 to promote Zero Dawn, Sony collaborated with special effects company Spectral Motion to construct a 13-foot-long, cable-driven animatronic Watcher suit that was actively piloted by an operator. ^{[76] [77]} To promote the global launch of Forbidden West in 2022, PlayStation commissioned massive, life-sized Clawstrider statues and placed them as temporary public installations in cities across five continents, including Dubai, London, New York City, Seoul, and Sydney. ^[78]

The machines' narrative was expanded in an official Zero Dawn comic book series published by Titan Comics, which featured a new breed of killer machines. ^[79] In 2020, Steamforged Games released Horizon Zero Dawn: The Board Game, a semi-cooperative miniatures tabletop game. ^[80] It was subsequently supported by multiple expansion sets adding miniatures of various machines including the Thunderjaw, Stormbird, and Fireclaw. ^{[81] [82]} The machines have also made multiple cameo appearances in other major video games. Machine-themed armour was featured in a crossover event for Monster Hunter: World (2018), and holographic versions of the Watcher and Tallneck appeared in Death Stranding (2019). ^{[83] [84]} The Thunderjaw appears in Ratchet & Clank: Rift Apart (2021) via a weapon that can summon it from another dimension, while other machines make an appearance in the Horizon-themed level of Astro Bot (2024). ^{[85] [86]}

Following the release of Zero Dawn in 2017, the franchise's machines expanded into various merchandise items and collectibles. To coincide with the game's launch, a special "Horizon Zero Dawn Thunderjaw Collection " was produced, featuring a highly detailed statue of the Thunderjaw. ^[87] That same year, two Watcher Funko Pop variants were released and in 2020, a Thunderjaw Pop was released. ^{[88] [89]} Also in 2020, a 26-inch premium statue of the Stalker was announced by Prime 1 Studio. ^[90] Merchandising expanded further alongside the launch of Forbidden West in 2022. The game's premium Collector's and Regalla editions included statues of the Tremortusk. ^[91] That same year, The Lego Group released a 1,222-piece set of the Tallneck. ^[92] This was followed by high-end collectibles, including a 15-inch Moderoid model kit of the Thunderjaw by Good Smile Company in 2023. ^[93] In 2025, a Lego set based on Lego Horizon Adventures was released, featuring buildable versions of the Shell-Walker and Sawtooth. ^[94] Later that year, Wizards of the Coast announced a Magic: The Gathering Secret Lair Drop featuring alternate-art reskins of cards depicting the Thunderjaw, Horus, Tallneck, and Plowhorn. ^{[95] [96]}