Old World Blues

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 Mountain' 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 Big Mountain in search of technology that can either turn the tables on the kidnappers or help them defeat an even greater threat.

After being transported to the Big MT research crater, you find that 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 Mountian 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 experience points that are rewarded for quests is based on the players level upon quest completion. The total experience points available for the main storyline quests is anywhere between 3,000 (for levels 1-4) to 22,000 (for levels 45-50). The side quest experience points ranges from 75 to 500 per quest.

Behind the scenes

 * The Big Empty was a location that was scrapped from Black Isle's canceled Fallout 3 (Van Buren).
 * 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.
 * This add-on is an obvious homage to the B-movie science fiction movies of the 1950s. There are many references to these types of movies throughout the add-on.

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 while indoors. To prevent freezing while in the Sink, enter Big MT from the Think Tank entrance.
 * Even though you take all of the contents inside a storage container, it will not say that 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. However, it's still possible to discover them afterward.
 * If you bought all three add-ons, your max level still might be 40. On Xbox 360, you can get rid of it by going the Dashboard and reloading the game.
 * Even though this is only the third add-on, the level cap will change to 50.
 * When returning to the Mojave, you may find your ratings with factions having diminished.
 * When loading an auto-save with Hardcore Mode turned on, your starvation and thirst meters will jump up over 200, despite those levels being low when the auto-save was created.
 * In-game time may pass abnormally fast. For example, a few in-game days may pass for a whole year according to the calendar.
 * 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 Victor or anyone on the Strip. This prevents you from using the Lucky 38 as a base. A way around it is to kill Victor and the rest of the Securitrons.
 * You may be unable to get caps for selling items to the Sink Central Intelligence Unit, and his stock will not replenish correctly. Make sure his cap total does not exceed 32,000 to prevent this.
 * When checking the DLC content on the main page, it may not show up but yet all content will be there when you begin playing.
 * With Old World Blues installed the amount of 5mm rounds found in containers and other sources of loot is reduced dramatically, to roughly 30% of what is normally found. This change only affects containers found in the Mojave Wasteland, and not those located in the Big MT.
 * Most members of the Brotherhood of Steel become notably weaker once Old World Blues is installed, reducing their Strength and Endurance stats by 3 and 2 points respectively, and removing Explosives as a tagged skill. This affects both unnamed members, particularly those found patrolling the area around Hidden Valley, as well as some named members including Linda Schuler, Knight Lorenzo, and even Nolan McNamara and Edgar Hardin.
 * Dead Money Perk Old World Gourmet is no longer working.