Dead Money

 is the first add-on for Fallout: New Vegas, developed by Obsidian Entertainment and published by Bethesda Softworks, to be released on December 21, 2010 for the Xbox 360 platform.

On November 17, 2010 Dead Money was announced by Major Nelson[3] and Bethesda[1]. It will be exclusive to Xbox Live.

Overview
Dead Money is set in the Sierra Madre, an opulent and extravagant resort that was supposed to be the greatest casino in the west – except that it never opened. Bombs fell before the gala opening, and the Sierra Madre froze in time, its state of the art security system locking the place up tight. Nothing could get in, and none of the guests could escape. Years passed. The climate control and air conditioning system within the facility began to spit toxins into the surrounding city, causing a slow cloud and haze to form over the area - which proved lethal to anyone who tried to explore the city. Only a mysterious group called the Ghost People survived to call the city home, trapped inside what appeared to be hazmat suits and never speaking to their victims... only capturing them alive and dragging them away to the depths of the city deep within And so the Sierra Madre faded from the history books, only occasionally being seen in posters across the wastes, until it took on mythic ghost story status... a supposed "City of Gold" in the Mojave Wasteland where all the treasures of the Old World were rumored to be held. It was kept alive as a late-night saloon story by prospectors who'd claimed to have found maps leading there... and were willing to part with the "map" for a few caps. Or a drink. Or a warm place to sleep.

The Sierra Madre is a mythical place in the wastes, with travelers all risking their lives to find it. Only one man truly "found" it - and lived. After the fall of HELIOS One, Father Elijah of the Brotherhood of Steel set out to find new weapons to eradicate NCR. And in the process he found the Sierra Madre. The Courier is lured to the Sierra Madre by a faint radio broadcast advertising the gala grand opening.

From a gameplay standpoint, Dead Money is accessed by loading a save file from any point in Fallout: New Vegas prior to the endgame sequence, in the same way as Operation Anchorage, Point Lookout, The Pitt or Mothership Zeta were triggered in Fallout 3.

This being an extension of Fallout: New Vegas, players will encounter several unique characters, each with their own motivations, all of whom will have to work together if any of them are going to survive. Aside from just struggling with their would-be companions, the courier will also have to deal with the mysterious Ghost People as well as the casino's substantial defense systems.

PS3 & PC
According to one or two other sites they claim it is coming out for more than the Xbox 360 but maybe at a later release date.