Fallout: New Vegas is an upcoming role-playing video game developed by Obsidian Entertainment and published by Bethesda Softworks. While New Vegas is not a direct sequel, it will use the same engine and be in the same style as Fallout 3, and is being developed by some of the people who worked on previous Fallout games at Black Isle Studios. It will be set in and around post-apocalyptic Las Vegas (New Vegas). It has a projected release date of Fall 2010 and will be available on the PC, Xbox
360 and PlayStation 3.
The game is set in a post-apocalyptic, retro-futurist Las Vegas following the Great War between the U.S., China and other countries, a conventional and nuclear war that occurred on October 23, 2077 and lasted less than two hours despite causing immense damage and destruction. Before the Great War were the Resource Wars, during which the United Nations disbanded, a plague rendered the United States paranoid, and Canada was annexed. The city of New Vegas itself didn't get hit as much as other districts, and most buildings were left intact. Hoover Dam supplies all the free electricity and water to those who control it.
StoryThe story will continue some parts of the Fallout and Fallout 2 stories, but will not be related in any way to the one in Fallout 3.
Fallout: New Vegas will take place in 2280, 3 years after the events of Fallout 3 and 39 years after Fallout 2, making this installment set the farthest in the series. The New California Republic will play a major part in the story, in a three way struggle between the NCR, the Caesar's Legion slavers, and the local New Vegas populace.
The player will play as a courier, who was left to die in a shallow grave, rescued by a TV Robot named Victor, and patched up by a Doctor Mitchell. 
GameplayThe gameplay system will be similar to the Fallout 3 gameplay, although some changes have been made.