PARAGRAPHFallout: New Vegas is a post-apocalyptic action role-playing video game developed by Obsidian Entertainment and published by Bethesda Softworks. A spin-off of the Fallout series, the game is set in a post-apocalyptic open world environment that encompasses a region consisting of Arizona , California , and Nevada. It is set in a world that deviated onto an alternate timeline thanks to Atomic Age technology, which eventually led to a global nuclear apocalypse in the year in an event referred to as "The Great War", caused by a major conflict between the U. The main story of New Vegas takes place in the year , four years after the events of Fallout 3 and years after the bombs fell. It is not a direct sequel , but does mark the return of several elements found in Fallout 2.