- "You're an ugly one, aren't you? No wonder you hide your face underground."
- ―Aloy, upon sighting a Rockbreaker
The Rockbreaker most closely resembles a badger or a mole with a flat and durable body, broad shoulders, and powerful front legs, although, unlike such creatures, this machine has a tail making up about a quarter of its length. Its most prominent feature is the massive maw of a tricone roller drill mounted on its head, each drill bit is set on jaws to allow the mouth to open and close. It is a quadruped, the front pair of legs sporting huge claws. Under the machine's belly is a fuel sac filled with Blaze and an exhaust port is positioned atop the body at the base of the tail.
Rockbreakers seem to be one of the original Acquisition-class machines created by GAIA to terraform Earth after its sterilization at the hands of the Faro plague in the mid-21st century. They have likely been around since before humans reappeared. While other mining machines like Lancehorns are able to gather materials from the surface, the Rockbreaker can tunnel deep into the earth to gather valuable raw materials for use in the Cauldrons.
After the Derangement, an event which caused all the existing machines to become more aggressive towards humans, the Rockbreaker's frightening speed, rugged design and powerful tools made it a menace to any humans nearby. By the time Aloy learned to hunt and fight machines, Rockbreakers attack any human they detect.
Like all machines, with the exception of the Tallneck, Rockbreakers attack humans once aware of his/her presence. They behave like a "land shark," tunneling around leaving a small dust wake to mark its position.
- Drill: This enormous tricone roller drill allows the Rockbreaker to tunnel through the ground to attack the target. Soft ground like sand or dirt is a danger zone in Rockbreaker territory and its drill will inflict massive damage if it connects. The drill, however, cannot burrow through rock.
- Digging arms: These appendages are tipped with powerful claws and allow the Rockbreaker to locomote on the surface as well as underground. These, coupled with the drill, allow a Rockbreaker to move as quickly and smoothly underground as a fish swims through water.
- Sound detection: If a human walks or shoots an arrow into the ground while a Rockbreaker is nearby, the machine will immediately be alerted and will tunnel straight to the exact location of the sound, regardless of the surface walked on or if Aloy is hiding in tall grass.
- Mobility: The Rockbreaker can move so fast that even an athletic human being like Aloy cannot outrun it, and it can breach the surface like a whale to carry out an attack, only to just as quickly dive underground again.
- Rock launching: If the target is out of melee range or standing on a rock, the Rockbreaker can regurgitate a stream of boulders projectiles similar to how a Behemoth can.
- Fire resistance: The Rockbreaker's chassis is resistant to fire weapons.
As formidable as they are, Rockbreakers have weaknesses that may be exploited to eventually kill them. They are as follows:
- Digging arms - removal of these will prevent it from going underground. However, all four arms must be removed.
- Fuel sac - puncturing this will cause an explosion that causes significant damage. However, the explosion also damages anyone within the blast radius.
- Exhaust port - strikes on this component deal greater damage to the machine.
- Freeze weapons: While resistant to fire, Freeze ammunition will freeze the Rockbreaker much quicker than other machines, slowing it down and making it more susceptible to damage.
The Rockbreaker only spends brief moments above ground, so it is best to remove the digging claws as quickly as possible, using Tear weapons, to negate its digging ability. As long as it can quickly dive underground, it can break any Ropecaster ropes used on it. It is also difficult to freeze because it will retreat before enough Freeze ammunition can be used. However, every once in a while it will, rather than surfacing vertically, will attack at an angle and, if dodged, will become "beached" on the surface, providing a longer window to immobilize it.
Even without legs, the Rockbreaker can still move fast on land, so the Ropecaster should be used to restrain it and freeze weapons to slow it down even more once the legs are gone.
One way to kill a Rockbreaker is to use a Tripcaster and to take advantage of its sound detection. Once you have located the Rockbreaker, set a trap of Blast tripwires stacked atop each other in one spot (the number of bombs needed depends on the difficulty and damage modifiers). The Rockbreaker will not hear this, so as long as Aloy crouches she will not be detected. Once the trap is ready, back up and shoot an arrow into the ground in the middle of the trap. The Rockbreaker will surface right onto the bombs and immediately be destroyed or badly damaged.
- The Rockbreaker shares many similarities with Nibelsnarf of the Monster Hunter franchise. Both have similar body shapes, methods of attack and movement, and a vulnerability to freezing/ice damage.
- A cone roller drill head design is made specifically for drilling through solid rock, commonly to gain access to ground water, oil, or natural gas because the objective is to not selectively mine ore. The fact that the Rockbreaker cannot drill through rock is likely due to balancing.
|Acquisition Class||Broadhead - Charger - Glinthawk - Grazer - Lancehorn - Rockbreaker - Scrapper - Snapmaw - Strider - Trampler|
|Combat Class||Ravager - Sawtooth - Stalker - Stormbird - Thunderjaw|
|Recon Class||Longleg - Watcher (Redeye Watcher) - Tallneck|
|Transport Class||Behemoth - Fire Bellowback - Freeze Bellowback - Shell-Walker|
|Chariot Class||Corrupted Machines - Corruptor - Deathbringer - Metal Devil|