Editing Machines (Horizon) (section)

== Concept and creation ==

=== Origins and visual design ===
[[File:Giraffe Mikumi National Park.jpg|thumb|upright=0.8|[[Giraffe]]s served as the primary visual inspiration for the Tallneck, the only machine in the franchise that is entirely peaceful and cannot be harmed.<ref name="Artbook" /><ref name="GBHZDMachines" />|alt=A giraffe facing left and standing in grass with a tree to its right]]

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.<ref name="NoClip" /> 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.<ref name="GIOrigins" /> 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.<ref name="MachineConcept" /> 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 [[Phorusrhacidae|terror birds]], and Watchers by [[meerkat]]s and small bipedal [[dinosaur]]s.<ref name="Artbook" /> 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]].<ref name="HFWReBuilding" /><ref name="Function" />

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]].<ref name="HFWReBuilding" /> For ''Forbidden West''{{'s}} [[Expansion pack|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.<ref name="Waterwing" /> 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 [[insect]]s, [[arachnid]]s, and [[crustacean]]s to emphasise their original purpose as hostile weapons.<ref name="Artbook" /> 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.<ref name="HorusBoss" />

=== 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 [[lobster]]s. 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.<ref name="LivingCreatures" /> 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.<ref name="Outsourcing" />

[[File:Early Thunderjaw Prototype for Horizon Zero Dawn.jpg|thumb|An early in-engine prototype of the Thunderjaw, constructed from a [[Lego Duplo|Duplo]]-like 3D model.|alt=A person shooting a gun at a grey dinosaur with red areas and green antennas]]

The game's overarching mechanics were established through technical prototypes. An early machine dubbed the "Predator" appeared as a holographic [[Easter egg (media)|Easter egg]] in ''[[Killzone Shadow Fall]]'' (2013), with many of its behaviour routines eventually adapted for the Sawtooth.<ref name="2YearAnniversary" /> 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.<ref name="MachineConcept" /> 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, "[[Lego Duplo|Duplo]]"-like 3D models with basic animations.<ref name="GIOrigins" /> 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.<ref name="LivingCreatures" /> These systems were then scaled down and integrated into smaller machines to ensure combat remained readable.<ref name="NoClip" /> 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.<ref name="LivingCreatures" /> 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.<ref name="IGNLegoAdventures" />

=== 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.<ref name="LivingCreatures" /> 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 lion]]s 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 panda]]s.<ref name="GRAnimals" /> 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.<ref name="GIMachines" />

[[File:Horus Concept Art for Horizon Forbidden West Burning Shores.jpg|thumb|left|Concept art of a Horus, which were designed to visually demonstrate the apocalyptic destruction of the Old World. Senior Art Director Misja Baas said that their design allowed the developers to "drape the machine on the landscape and make it look very dynamic", serving as environmental storytelling that captures the last moments of life on Earth.<ref name="HorusBoss" />|alt=A large mechanical machine with multiple long legs and the partially destroyed Hollywood Sign]]

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.<ref name="HorusBoss" />

Sound designers balanced robotic and animalistic noises to create an "emotional impact", an approach the audio team dubbed "natural-fiction".<ref name="NaturalFiction" /> 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.<ref name="GuerillaAudioInterview" /> 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.<ref name="GIMachines" /> To guide these vocalisations, the designers [[anthropomorphism|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 (dog breed)|Chihuahua]]".<ref name="NaturalFiction" /> 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.<ref name="GIMachines" />

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.<ref name="NaturalFiction" /> To ground the machines in the world, the audio team created unique [[Foley (filmmaking)|Foley]] for machines walking across different terrains to convey their weight.<ref name="GIMachines" /> 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.<ref name="GuerillaAudioInterview" /> 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.<ref name="NaturalFiction" />

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,<ref name="GuerillaAudioInterview"/> altering a machine's vocalisations dynamically based on whether it is suspicious or aggressive.<ref name="GIMachines"/> 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.<ref name="HFWReBuilding" />

=== 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.<ref name="HFWReBuilding" /> To dictate machine behaviour, the developers used [[hierarchical task network]] (HTN) planning, allowing the [[Artificial intelligence in video games|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.<ref name="BehindTheAIP1" /> 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]].<ref name="BehindTheAIP2" />

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.<ref name="GIOrigins" /> The player can also hack or "override" machines using a device attached to [[Aloy]]'s spear.<ref name="AloySpear" /> While some overridden machines can be used as ridable [[Working animal#Riding animals or mounts|mounts]], others will only temporarily fight alongside the player.<ref name="HZDOverrides" /> The developers chose not to let the player directly control the machines' actions after overriding them, ensuring they remain independent entities within the ecosystem.<ref name="ControlMachines" /> In ''Forbidden West'', this mechanic was slightly expanded, allowing the player to specify whether an overridden machine should take aggressive or defensive stances.<ref name="OverrideSubroutines" />

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.<ref name="HFWReBuilding" /> The developers also integrated human and machine factions more closely, designing encounters where human enemies actively commandeer machines.<ref name="Evolving" /> To increase the challenge, the game introduced "Apex" variants: heavily armoured, deadlier versions of standard machines.<ref name="GDCHFW" /> 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.<ref name="UEHCM" /> 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.<ref name="RoadToVR" />

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 game|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.<ref name="HSFMachineCombat" /> Alternatively, Guerrilla's upcoming PS5 and PC [[Cooperative video game|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.<ref name="HHGStyle" />