Old World Blues (quest)

Old World Blues is the final main quest in the Fallout: New Vegas add-on, Old World Blues.

Synopsis
With all the technologies retrieved, it is time to confront Mobius at the Forbidden Zone... or is it time to confront the Think Tank?

Walkthrough

 * 1) Talk to Dr. Klein after retrieving all of the technologies required.
 * 2) Enter the Forbidden Zone Dome entrance.
 * 3) Defeat or disable the X-42 giant robo-scorpion.
 * 4) The room farthest to the right with stair leads to a terminal that activates X-42 backup generator, which overloads and damages the X-42 giant robo-scorpion.
 * 5) The room on the left has a terminal that requires a Science of 50 to hack and allows turrets to turn on the X-42 giant robo-scorpion and deal some damage to it.
 * 6) To the right is a room that has a switch to activate the Protectron target drones, which will distract the robo-scoprion.
 * 7) The balcony room on the far left contains a terminal that requires a Science of 100 to hack; alternatively the password is on a holotape to the right of the rightmost protector bay. The terminal allows the option to permanently shut the robo-scorpion down.
 * 8) Enter Mobius' lair and reason with or kill him.
 * 9) Reclaim or reason with your brain.
 * 10) Reason with or defeat the Think Tank.
 * 11) To reason with them, a Speech check of 75 is required, followed by a Medicine of 85 or a Science of 100. Alternatively, if the Courier completed at least three of the four Think Tank quests (What's In A Name?, On The Same Wavelength, A Brain's Best Friend and Coming Out of Her Shell) Klein can be told to confer with his colleagues, who will support the Courier's view.

Behind the scenes

 * If you finished three or more of the Think Tank's personal quests and ask Dr. Klein to consult his colleagues, having completed 8|Doctor 8's quest, when it is his turn to speak, Klein will say, "Et 2, 8?" in response, referring to Gaius Julius Caesar's last words to Marcus Junius Brutus. It is also a reference to another quest in Fallout: New Vegas, Et Tumor, Brute?.

Bugs

 * When the brain is asked if it wants to be reunited with you, choosing the compromise option, the second choice, will result in a never ending loop of the brain talking about the quests. This only seems to happen if the player has completed Come Fly With Me and That Lucky Old Sun. If this happens, reload the autosave where you entered Mobius' room and pick alternate dialogue options.
 * Before entering the Forbidden Zone Dome, it is advisable to make a new separate save as when entering through the main entrance into the arena with the X-42 giant robo-scorpion, it is possible to load under the catwalk and become stuck there.
 * After finishing this quest by either killing, or talking to the doctors in the Think Tank, the game may crash as the player tries to leave. This bug occurs when you have a hunger greater than zero, and, inherently, only in Hardcore Mode.
 * If certain choices are made in dialogue, it is impossible to reason with Mobius and killing him becomes the only option, even if the correct skill checks are completed. This is a similar situation to what may happen with Dean Domino in the Dead Money add-on.
 * A possible fix for this bug involves a repair check to fix Mobius' monitor, which can re-initiate the dialogue path needed to avoid killing Mobius.
 * When the protectrons inside the Forbidden Zone Dome are activated, a seemingly unlimited/invincible number of them may keep attacking the X-42, creating an effective distraction when attempting to destroy the X-42.
 * Even with all the holotapes located and installed, the only options available while interacting with the Sink Auto-Doc are heal yourself and respec your traits. This bug seems related only to the Spanish version of the game.