Fallout: New Vegas
Action role-playing open world video game developed by Obsidian Entertainment, and published by Bethesda Softworks. It was released for Microsoft Windows, PlayStation 3 and Xbox 360 in October 2010. The game is based in a post-apocalyptic environment in and around Las Vegas, Nevada.
The player takes control of "the Courier", who is hired by a delivery service to take an unknown package across the Mojave Desert to "The Strip" but intercepted, shot in the head, and left for dead by a mysterious man who steals the package. After being found by a friendly local robot, Victor, and healed by a man named Doc Mitchell, the Courier is thrust back into the desert to seek revenge and recover the stolen package. Through doing this, the player becomes caught up between various factions competing for control over the desert and it's most valuable asset, the Hoover Dam; ultimately coming to shape the future of its inhabitants.
In the first DLC pack, named Dead Money, the Courier is captured by an insane ex-Brotherhood of Steel leader known as "Father" Elijah and must work alongside three other captives to find the fabled treasure of the Sierra Madre Casino. The pack adds new achievements/trophies, perks, terrain, enemies and decisions for the player, as well as raising the level cap by 5.
In Honest Hearts, the Courier is part of an expedition to Utah's Zion National Park, when they are attacked by tribal raiders. While trying to return to the Mojave, the player becomes involved in conflicts between the tribes and between a "New Canaanite" missionary and an individual known as the "Burned Man", Caesar's former Legate, who, after losing the first battle of Hoover Dam, was covered in pitch, set on fire, and thrown into the Grand Canyon. The pack adds new achievements/trophies, perks, terrain, enemies and decisions for the player, as well as raising the level cap by 5.
Old World Blues
In Old World Blues, the Courier unwittingly becomes a lab rat in a science experiment gone awry and discovers how some of the Mojave's mutated creatures came to exist. Old World Blues takes place in the Pre-War research centers of Big Mountain, known colloquially as "the Big Empty" or "Big MT" (where Father Elijah had found most of his equipment prior to Dead Money, such as the bomb collars and the holorifle, along with Christine also from Dead Money). The player can also choose to either turn on their kidnappers or join with them to fight an even greater threat. This pack offers new achievements/trophies, perks, a vast area to explore, and raises the level cap by 5 like the previous two packs. The player can only explore in the area until the main storyline of the DLC has been completed, but after completing it, can return back to the area at will.
Lonesome Road concludes the story of the Courier, focusing on Ulysses, a former Frumentarii of Caesar who had discovered the "Divide": a glorious land until the New California Republic annexed it. This caused Caesar to retaliate and send a small army to seize the Divide, resulting in the NCR ordering the Courier to deliver a package which would trap the armies of the NCR and the Legion and turn the Divide into a tornado strewn land full of ghouls, called Marked Men, and other dangers. Ulysses believes the Courier to be responsible for the mess of the Divide and when he is ordered to deliver the Platinum Chip, he realizes Benny's plan and discovers the Courier to be alive. When discovering the Courier is not dead, Ulysses contacts the Courier and asks him/her to enter the Divide, evoking the start of Lonesome Road.
Gun Runners' Arsenal and Courier's Stash
Gun Runners' Arsenal adds various new weapons and weapon mods (along with new ammo types) to the game, which can be found throughout the game world. Courier's Stash contains all bonus content that was previously only available for pre-ordering the game (the Caravan Pack, Classic Pack, Mercenary Pack and Tribal Pack).
Source: Wikipedia, "Fallout: New Vegas", available under the CC-BY-SA License.