The original robo-scorpion was created before the Great War by Dr. Mobius and his team in the X-42 robo-warfare facility in Big MT, based on scorpions and powered by a fission battery. They were created for security at the Big Mountain Research and Development Center as robotic guardians with a tail-mounted energy bolt blaster, optical systems allowing anyone in the X-42 robo-warfare facility to see through them with monitors, and a self-destruct sequence which, after their death, causes electrical explosion damage to anyone around. Additionally, their public address systems allow anyone in the X-42 robo-warfare facility to speak through them. According to Mobius, they can form themselves from floor panels along with any other random parts lying around. X-42 giant robo-scorpions, unlike the others, were a project for the US military. Despite 18 prototypes being requested, certain kinks in design and programming prevented them from reaching battlefield deployment and only one functional prototype was completely finished, remaining idle in the X-42 robo-warfare facility.
Sometime after the Great War, Mobius hacked his colleagues and altered their personalities, chronometers, geometers and more. Disgusted by his actions against his friends Mobius erased some parts of his own memory to ease his conscience, including the knowledge of his creations. Later, Mobius relocated to the X-42 robo-warfare facility which he renamed the "Forbidden Zone." There he began to "re-create" the robo-scorpion, now based on the radscorpions which occasionally wandered into the Big MT. He added the suffix "b" onto his new creations and retained all features of the pre-War model. He also took control of the previous models of robo-scorpions making them his personal army. Mobius now uses the robo-scorpions to constantly distract the Think Tank.
Robo-scorpions are very fast and extremely resistant to most damage. Pulse weapons are less effective against them compared to other robots. The X-42 giant robo-scorpion is a special model adorned with Saturnite armor plating, making it virtually impervious to small arms fire, and an improved EMP shield. Its tail is equipped with a powerful atomic laser that draws its energy from an internal generator. The laser is capable of causing severe damage and leaving residual radiation of about 30 rads per second for one second, as well as having a blast radius of about 3 meters. It is also equipped with a self-destruct system like other robo-scorpions, but detonates a small nuclear device instead of an electrical explosion. The X-42 Giant robo-scorpion's self-destruct explosion leaves radiation of about 15 rads for the first second which decreases every subsequent second, stopping after five seconds.
Robo-scorpions appear in Mk. 1-5 and Mk.1b-5b, and come in pincer, blaster, and bomber variants, as well as different sizes relative to their Mark. Their appearance in the game depends on the player level and importance of the location in which they appear.
Encountered in the Forbidden Zone dome during the Old World Blues quest, the X-42 giant robo-scorpion is a unique robo-scorpion and Doctor Mobius' ultimate guardian. It is armed with a powerful atomic laser capable of causing severe damage and radiation damage of about 30 rads per second for one second as well as having a blast radius of about that of a pulse grenade.
It sometimes fires at you while you are behind cover, and you will still absorb the reduced amount of radiation, about 2-15 rads per second.
All robo-scorpions can be disabled with the Robotics Expert perk, including the X-42 giant robo-scorpion. However, the X-42 giant robo-scorpion will restart itself after a set amount of time has passed, a unique feature compared to all other robots. You can exploit the latter for unlimited xp by deactivating the X-42 giant robo-scorpion again and staying hidden when it reactivates.
The X-42 Giant Robo-Scorpion cannot be deactivated with the Robotics Expert perk if it has been put into emergency shutdown.
Robo-scorpions are normally found in groups of 2-4.
Even if you team up with the Think Tank and Mobius after completing the Old World Blues quest, robo-scorpions are still hostile to you.
The legs of a giant robo-scorpion, much larger than the X-42, can be seen poking out of the ground next to the Waste disintegration platform. Later, you learn through terminals and Mobius' declarations that once a bigger version of the X-42 giant robo-scorpion became frenzied and left the Forbidden Zone and started consuming a lot of energy, so Mobius had to disable and dispose of it.
The X-42 giant robo-scorpion explodes upon death in a similar manner to how Gabe explodes, should he be killed in A Brain's Best Friend. The explosion leaves radiation around and lowers at the same rate as a Fat Man.
As seen in the trailer, X-42 giant robo-scorpion was to appear in Higgs Village, but that encounter was removed in the final release for some reason.
The X-42 giant robo-scorpion is the largest enemy the Courier comes across without using console commands.
The robo-scorpion will explode despite being melted or disintegrated by laser/plasma energy weapons.
↑One robo-scorpion appears in the Big MT's snow globe and snow globes were manufactured before the Great War. Also, tests on some X-42 giant robo-scorpions prototype was performed before the Great War as can be seen on the terminals of the X-42 robo-warfare facility, but despite 18 prototypes being requested, only one functional prototype exists. In addition, when you take the Audio Sample - Mobius' Robo-scorpion, a message says "This holotape contains an audio sample from Mobius' giant robo-scorpion".