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 night stalkers) came into being while unwittingly becoming 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 your kidnappers or help them fight against 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 and an evil scientist who threatens their lives. As you explore the Big Mountain 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 and hunt down your own brain, spine and heart which have been removed from your person in an experiment.

Quests
The experience points that are rewarded for quests are 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 cancelled 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.
 * 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.
 * Old World Blues was nominated for Best DLC Award at the 2011 Spike Video Game Awards. It was the only one of the Fallout: New Vegas add-ons to be nominated.