I haven’t read the design docs for Van Buren myself, were there enough in there to actually build a game out of or is this project more fanfiction and educated guesswork?
sounds like fanfic.
In practice, this is a total conversion for Fallout 2, reshaping the isometric classic with new characters, quests, story missions, weapons, and items based on what the Fallout community has learned about Van Buren over the years.