Old World Blues

"There is an expression in the Wasteland: "Old World Blues". It refers to those so obsessed with the past they can't see the present, much less the future, for what it is."

- Doctor Mobius and Doctor Klein

Old World Blues is the third add-on for Fallout: New Vegas, developed by Obsidian Entertainment and published by Bethesda Softworks.

Plot
"The residents of the Mojave have long assumed the trackless wastes of the ‘Big Empty’ are a no-mans' land, a desolate stretch where no living thing can survive. In Old World Blues, you discover that it is anything but..."

In Old World Blues, the Courier discovers how some of the Mojave’s mutated monsters (cazadores and nightstalkers) came into being whilst he or she unwittingly becomes a lab rat in a science experiment gone awry. The Courier must scour the pre-War research centers of the Big Empty in search of technology to turn the tables on his or her kidnappers, or join forces with them against an even greater threat.

After being transported to the Big MT research crater, you find you're the only hope of saving the "Think Tank" – a strange group of post-human researchers who inhabit the facility. They enlist your aid to save them from their own experiments - experiments that have gone horribly out of control. As you explore the Big Empty crater and its many underground labs, you’ll confront strange mutated animals, battle terrifying new atomic robots and discover a new home base to call your own. Recover all the weapons, armor and tech of the pre-War era and use them to help save all of science!

Quests
The XP that is rewarded for quests is variable based on your level upon quest completion. The total XP split between the main storyline quests is approximately 3000 XP at levels 1-4 and 22000 XP at levels 45-50, the secondary quest XP ranges from 75 XP per quest to 550 XP per quest.

Behind the scenes

 * The Big Empty was a location that was scrapped from Black Isle's canceled Fallout 3.
 * At some point, Chris Avellone set his location on his Twitter profile to Big MT, Mojave, placing the Big Empty as a location within the Mojave Wasteland and thus teasing its possible appearance in a future Fallout: New Vegas add-on. Since then, Avellone has also changed his Twitter avatar.
 * J.E. Sawyer has suggested that Old World Blues will be the most humorous of the New Vegas add-ons.

Bugs

 * Entering the Big Empty then saving your game, waiting, or entering doors may cause the game to freeze. A way to work around this is to never save or wait in Big MT itself, but indoors and to prevent freezing when in the sink enter Big MT from the Think tank entrance.
 * Opening a storage container, taking all of its contents, and leaving, the container may not say it is empty.
 * Similar to a bug in Honest Hearts, while playing through the main quest, the tick marks of undiscovered locations can disappear from the compass. It's still possible to discover them afterward though.
 * Some armors may degrade very quickly while playing.
 * If you bought all three add-ons your max level still might be 40 but you can get rid of it if you go on the Dashboard and reload the game.
 * With this add on, the max level has been raised to level 50, the max level with all four add-ons.
 * When you return to the Mojave, you may find your ratings with factions have diminished.
 * When loading an autosave with Hardcore Mode turned on, your starvation and thirst meters will jump up over 200, despite those levels being low when the autosave was created.
 * In-game time may pass abnormally fast, the calendar registering up to an entire year passing with what seems to only have been a few in game days in some cases
 * After completing Old World Blues you may find yourself attacked on sight by the Brotherhood of Steel upon re-entering the bunker, or by the caretaker of the Brotherhood of Steel safe house, even though your standing with them is unchanged.
 * The first time you load Old World Blues, the game may be unresponsive, but you can still be in party chat, when the purple screen that says, "Fallout: New Vegas Old World Blues" comes on.
 * When talking to your brain after defeating Mobius, you get stuck in an infinite loop of a conversation concerning pleasant memories about Helios One and Jason Bright (Quite the ironic bug considering the conversation you just had with Mobius!).
 * When returning to the mojave you may not be able to talk to vincent or anyone on the strip. This prevents you from using the tower to as a base. A way around it is to kill vincent, and the tower securitrons.