The Doom Bible is the original design document for Doom, written by Tom Hall in 1992. Much of the content seen in the document is not featured in the final version of the game.
I think this is a very interesting story. I don't really think it would have worked at the time just because of how big and convoluted the story is if it were made now I think it would have been the best game ever. I'm thinking about writing a book using the Doom Bible. The story and everything. overall really good.