Fallout: New Vegas is a post-apocalyptic role-playing video game developed by Obsidian Entertainment and published by Bethesda Softworks. While New Vegas is not a direct sequel, it is in the same style as Fallout 3, and has been developed by some of the developers of Fallout and Fallout 2. It is set in and around New Vegas, the Fallout-equivalent of Las Vegas.
Mods and standalone-isque projects made for New Vegas are created with the Garden of Eden Creation Kit, which is ran on the Gamebryo game engine. According to Nexus Mods, New Vegas has over 17,259 mods and projects available. Several of those mods are listed here. Mods listed range from PG to adult-related content.