- "You're an ugly one, aren't you? No wonder you hide your face underground."
- ―Aloy, upon sighting a Rockbreaker
The Rockbreaker is a machine in Horizon Zero Dawn. It is a large Acquisition Class machine, and one of of the largest known machines. It is unique among Acquisition Class machines and machines in general in that it is the only known machine capable of subterranean ambulation. Its main purpose is the underground mining of mineral resources. However with the onset of the Derangement, its huge size, power and subterranean ability have been turned toward attacking any human it senses walking the ground above it, ambushing the target with lethal results.
Rockbreakers were created by the Zero Dawn terraforming system’s governing artificial intelligence (AI) GAIA as one of the machines designed for terraforming the Earth after it was left lifeless and sterile by the Faro Plague in the mid 21st century. However, after GAIA self-destructed, the AI HEPHAESTUS, formerly a subordinate function that manufactured machines under GAIA’s direction, gained control of five Zero Dawn cauldrons and the machines they produced, including Cauldron ZETA, which produced Rockbreakers. It altered the behavior of these cauldrons’ machines toward humans from docility to hostility.
The Nora huntress Aloy encountered Rockbreakers during her journeys in the Carja Sundom and environs, and in the Banuk region known as The Cut. At the Cut-Cliffs quarry, she investigated a series of gruesome deaths and discovered them to be the work of a Rockbreaker, which she engaged and killed when it attacked her. Assisting in the defection of the Carja prince Itamen and his mother Nasadi from the Shadow Carja, she was told of a Rockbreaker that prowled a gorge through which they had to pass during their escape from the Shadow Carja. She engaged and killed it before they arrived. She also encountered two Rockbreakers at a site in the Rustwash region. Finally, she encountered two Corrupted Rockbreakers at a corrupted zone east of the Sun Furrows Hunting Grounds, and hunted a Daemonic Rockbreaker dubbed "The Claws Beneath" in a remote valley in The Cut.
A Rockbreaker’s chassis closely resembles the body of a badger or a mole, though unlike these animals, it has a tail whose length is approximately one quarter of the length of its body. Its most prominent feature is a massive mouth, composed of an enormous roller-cone drill bit. Each cone is set in a hinged jaw. This configuration allows the bit, and therefore the mouth, to expand as needed. Twin optical sensor arrays are located in the same position on the head as a mole’s eyes. However, while a mole has very poor eyesight, a Rockbreaker’s optical sensors are fully functional. At the end of each of its four short, stout, powerful limbs is a large extremity called a digging arm that resembles an excavator’s shovel. Under the machine's belly are twin Blaze sacs, and twin exhaust ports are positioned atop the body at the base of the tail.
The Rockbreaker is built for underground mining operations, tunneling through rock and soil with its mouth, ingesting large quantities of rock, which it processes and extracts mineral resources from. It surfaces frequently to expel large boulders, presumably boulders of processed rock, from its mouth. During activity, it may form a mound of rubble on the surface containing resources that humans find useful. At intervals it rests on the surface for a short time, presumably to release accumulated exhaust, before descending underground again. Like all large machines, Rockbreakers are never found in groups of more than two. The mineral resources that it extracts are presumably collected for transport to cauldrons to manufacture new machine units. Post-derangement, it was also used as a means of area denial against human interlopers; when the one that Aloy killed in the gorge between the Branded Shore and Shadow Carja territory first appeared, the Shadow Carja allowed it to remain there to discourage the use of this gorge to access their territory.
A Rockbreaker’s most formidable ability is its subterranean capacity; it can emerge from the ground, attack, then immediately return underground to emerge and attack at another position entirely. This ability works in tandem with the speed at which it ambulates underground; a Rockbreaker “swims” through the ground below the surface with the ease of a shark swimming underwater. Thus it can repeatedly emerge, attack, return underground and change position at very high speed. The only indication of its location is the dust trail and rumbling sound that the ground produces when the machine is moving near the surface. Furthermore, the Rockbreaker’s subterranean ability makes putting it into an elemental state difficult, as it hinders the repeated strikes from elemental weapons needed to cause such a state. This is also the case with tying it down; by going underground, the Rockbreaker breaks any attached Ropecaster lines before full tie-down is achieved.
Rockbreakers are sensitive to sound. If a human walks or runs on ground under which a Rockbreaker is present, it will zero in on the sound and attack. If a projectile or energy weapon is fired, the Rockbreaker immediately zeroes in, not on the sound of the projectile or energy bolt striking, but on the sound of the weapon being fired. This includes the relatively quiet sound of a bow release.
Rockbreakers mainly employ melee attacks, most of which utilize their ability to emerge on the surface at high speed. However they can also ambulate on the surface with surprising speed, and are actually capable of overtaking an athletic human at full run. Additionally they employ a ranged attack in which they hurl boulders from their mouths at an enemy.
Rockbreakers are more susceptible to Freeze attacks than other machines, although putting them in a Freeze state can be difficult as previously explained. They are reliant on their four digging arms for tunneling underground; removal of all four arms prevents them from going underground, thereby disabling all of their subterranean attacks, and reduces their surface speed to a slow, hopping crawl. Ranged weapon strikes on their exhaust ports inflict significant damage. Destruction of each fuel sac triggers a large explosion that will apply the burning effect. Finally, they are unable to dig under watercourses (likely a hardwired safety protocol); thus a hunter can move beyond all of their attacks save their ranged attacks by crossing a river.
|Name||Damage Type||Primary Damage||Secondary Damage||Trigger Range||Description|
|Leaping Crush||Melee||250||-||0m - 15m (surface to submerged)
0m - 24m (submerged to surface)
0 - 30m (submerged to submerged)
|Propels chassis out of ground and lands on enemy|
|Jaw Smash||Melee||200||-||0m - 14m||Lunging bite with jaws|
|Lunge Crush||Melee||200||-||10m - 19||Springs forward and lands on enemy|
|Shark Bite||Melee||200||-||N/A||Emerges vertically from ground to envelop enemy in jaws|
|Spinning Smash||Melee||180||-||0m - 10m||Rotating bludgeon attack with body|
|Rock Blast||Explosion||50 per rock||-||0m - 30m||Hurls boulders horizontally from mouth at enemy|
|Rock Volcano||Explosion||100||150 per rock||N/A||Hurls boulders vertically from mouth around body at the enemy|
- The Rockbreaker shares many similarities with the Diablos of the Monster Hunter franchise. Both have similar body shapes, methods of attack and movement, and a vulnerability to freezing/ice damage.
- Coincidentally, it was announced during 2017 Paris Game Week that Horizon: Zero Dawn will have special collaboration with the CAPCOM series, suggesting that Aloy's appearance and Zero Dawn-themed equipment will be accessible via DLC on Monster Hunter World, exclusively on the PS4 release.
- Another similarity the Rockbreaker has is with the 10th Colossus from Shadow of The Colossus game, another PlayStation-exclusive installment recently remade for PlayStation 4. Both are subterranean serpentine creature with split lower jaw that attack in a similar manner. The weak point of both creatures is also on their lower back.
- The Rockbreaker is the only large machine not involved in any part of the main quest.
- Rockbreakers seem to be extremely rare; the only known Rockbreaker site is the one in the Rustwash region, which spawns 2 units at a time. Any Rockbreakers encountered beyond this site are one-time quest-specific occurrences.
- Rockbreaker eyes have a wrench-like shape on them.
- Rockbreakers seem to attack all sources of sound, which could be the reason why other machines steer well clear of a Rockbreaker site.
|Acquisition Class||Bristleback - Broadhead - Charger - FireclawFW - FrostclawFW - Glinthawk - Grazer - Lancehorn - Rockbreaker - Scrapper - Snapmaw - Strider - Sunwing - Trampler|
|Combat Class||Clawstrider - Ravager - Sawtooth - ScorcherFW - Shellsnapper - Stalker - Stormbird - Thunderjaw - Tremortusk|
|Recon Class||Longleg - Watcher (Redeye Watcher)|
|Transport Class||Behemoth - Fire Bellowback - Freeze Bellowback - Shell-Walker|
|Chariot Class||Corruptor - Deathbringer - Metal Devil|
|Unknown Class||Burrower - Control TowerFW|
|Other||Corrupted Machines - Daemonic MachinesFW - "New breed"|