This is probably know by everyone already, but Van Buren was the code name to the original Fallout 3. It's very similar to the original Fallout's except it has a fully 3D engine and you can switch between the old fallout type of combat to the new kind. It was also to include a coop multiplayer. However it never went through after Bethesda bought the franchise. A few references to Van Burens plot were added into New Vegas.
There is a Tech Demo I recommend playing even though its horribly buggy and crashes every five minutes. Here's the download link and some screenshots.
Not that it really matters, the tech demo is only a couple of minutes long and that's all that exist of the game.
The game would have begun with the player in a prison cell. Because of this the player was given a choice. The prisoner could be an innocent that was imprisoned because of some misunderstanding, or they could choose to be a criminal and take bonus traits that would bolster some of their skills.
The player would awaken in a prison cell, but not the one they remembered falling asleep in. Suddenly the floor rocks violently from an explosion and the player is knocked unconscious. When they awaken, they find their cell door open and a hole in the wall leading outside. Leaving the prison, the character is under attack by some unknown assailant. Deciding that discretion is the better part of valor, the player flees into the night to explore this new world.
Unfortunately, this newfound freedom may be short lived. The player is relentlessly pursued by robots who want to return them to the prison. As they explore the world and try to outwit their pursuers, they begin to uncover an underlying plot. Why was the character in a different prison than the one they fell asleep in? Why can't they remember being transferred? What was the attack on the prison about in the first place? Then they find out about NCR's problems, and a few things don't add up....
Just like all the titles in the Fallout series, the story ends with multiple different endings for every community and faction that you interacted with. Their outcome depends on your actions. Eventually, the player would discover the true reason behind the prison and the attack on it. It turns out that through extensive research, the mad scientist called Presper, disgusted with what the world turned into after the War, discovered the history of New Plague, the virus that FEV was initially created to cure, and its genocidal potency, and also discovered a viable means to cleanse the world. Using ULYSSES, the quarantine prison, and a ballistic satellite known as B.O.M.B.-001, the way to human planetary domination and order became clear. He needed to get to B.O.M.B.-001 and use the nuclear weapons to clean the filth and wretch that currently have occupied the surface.
Presper and his followers released the New Plague virus in the remote areas near Boulder and Denver. It was close enough to the quarantine prison to spur ULYSSES into action, but not near enough to cause huge populations to start a general panic. Once enough people were infected and ULYSSES “arrested” enough people to just about fill up the prison, Presper’s men would stage an attack on the prison which would allow everyone to escape. This event would start a countdown of sorts for missile launch on B.O.M.B.-001. ULYSSES would assess the viral spread, try to gather up the escaped prisoners, and once 90% of the prisoners had been retrieved, launch nuclear missiles to “clean & prevent” any further infection. By the time this happened Presper had planned to be on, and in full control, of B.O.M.B.-001 and reprogramming targeting solutions to clean the areas he wanted. Humans of his choosing would wait out the second nuclear holocaust in the Boulder Dome, until the day came where he declared the Earth safe for pure blood humans once more.
