Bethesda Softworks' Pete Hines has described Fallout: New Vegas as "a massive game world that will take you hundreds of hours to explore every nook and cranny".
"There are casinos, and you can go down onto the Strip. It will have a very different feel from that standpoint."
There will be no direct connection to the events of Fallout 3, apart from a few hints here and there, but you still start out customising your character's gender, age, race, skills and attributes.
You also begin outside the Vault. As previously revealed, you're a courier who is robbed and left for dead before being nursed back to health. "Part of the story is finding out what you had and what they took."
The news comes at the same time as magazine reveals which have already spilled onto the internet, talking up the returning VATS system, different conversation options and other new elements.