Van Buren was the codename for a sequel to Fallout 2 being developed by Black Isle Studios until it was cancelled in 2003. Information about this lost Fallout 3 could have been having appeared online in the years since, lending it a mythic quality among Fallout fans. A group of modders are currently dedicated to recreating Van Buren as a New Vegas mod called Revelation Blues since InXile currently owns the Van Buren name.
“We will stay faithful to the original Van Buren story as much as possible,” says the project’s page on NexusMods, “and in the future we plan to add in a large number of customized features. As of now, the project is still a WIP.” You can download and play a demo of Revelation Blues from that page right now.