Shell-Walker

The Shell-Walker is a class of machine in Horizon Zero Dawn. It is a medium sized Transport Class machine, primarily functioning in the transport of resources gathered and processed by other machines to cauldrons. However, it was weaponized at the onset of the Derangement, and now poses a significant threat to any human who encounters one.

History
Shell-Walkers were presumably one of the machines designed by the Zero Dawn terraforming system’s governing artificial intelligence (AI) GAIA, to be used in the detoxification of the Earth after it was ravaged and left lifeless by the Faro Plague. Originally Shell-Walkers were docile towards humans, fleeing at the sight of humans, as did all terraforming machines. However, after GAIA self-destructed, the AI HEPHAESTUS altered the behaviour of Shell-Walker and all other terraforming machines, making them hostile to humans to the point of attacking them on sight. This phenomenon is what the tribes refer to as the Derangement. Furthermore, HEPHAESTUS weaponized Shell-Walkers, equipping them with electric attacks and a protective energy shield.

Appearance
A Shell-Walker’s chassis is crab-like in appearance. It has six stout crab-like legs connected radially to a body primarily composed of a platform upon which it carries a hexagonal cargo container. On the underside of the platform is a power generator. The container is presumably fastened to the platform electromagnetically. The head is laterally wide, with a triangular optical sensor array located at each end. Additionally a Shell-Walker has a pair of limbs that are akin to the chelipads of a crab. An energy shield generator is on the end on the left limb, and a weapon that fires projectiles of electrical energy, dubbed a lighting gun, is on the end of the right limb. A projection carrying a pair of long antennae protrudes vertically from the left side of the head.

Behaviour
Shell-Walkers may be found in groups of a few units at various sites in tribal lands. They mill about, communicating via electronic warbles. They also walk in machine convoys accompanied by Watchers or Longlegs, carrying their cargo to cauldrons. A Shell-Walker’s highest priority is the defense of its cargo. Indeed, the Spurflints Hunting Grounds Keeper advised the Nora Brave Aloy that “Shell-Walkers will defend their cargo with their lives”. If its Crate Holders are destroyed, Shell-Walkers use their Lightning Gun (if intact) to hold their cargo containers in place.

Shell-Walkers attack humans on sight. Upon identifying a human, a Shell-Walker will emit a loud, angry metallic warble, alerting other nearby Shell-Walkers or other machines, raise its energy shield and let fly at the human with shots from its lightning gun. If the human is at close range, it will resort to melee attacks. Shell-Walkers usually walk in a slow, precise manner. However when attacking, they ambulate with surprising speed. When engaging a perceived threat, a Shell-Walker ambulates in a manner that always keeps it facing the threat, allowing its energy shield to be most effective.

Abilities
A Shell-Walker’s shield generator produces a visible forward-facing energy shield that is impenetrable to projectiles, such as arrows. The shield can be activated and deactivated at will, and may be disabled by destroying the generator. A Shell-Walker also employs a number of offensive ranged electric attacks, a defensive radial electric attack, and melee smashing attacks. utilizing its shield, lightning gun and shield generator as bludgeons.