Fallout: Brotherhood of Steel 2 (lost build of unfinished PlayStation 2 game; 2000s)
Fallout: Brotherhood of Steel 2 was a cooperative Action role-playing game that was being developed by Interplay Entertainment for the PlayStation 2 in 2004. It was the scheduled sequel to Fallout: Brotherhood of Steel.
The game, set in and progressing through areas of Texas, follows a war waging between the Brotherhood of Steel and a raider group known as The Cyphers. The Cyphers are recognized as the exact opposite of the Brotherhood of Steel; driving to destroy technology and eradicate the Brotherhood of Steel. The Cyphers have come into possession of a G.E.C.K (Garden of Ethan Creation Kit). Miles Reese, whom discovered the device, intends to use it to destroy human life and create a new world, overrun by vegetation.
The gameplay was inspired by games such as Baldur's Gate: Dark Alliance, Diablo 2, Fallout Tactics, and the two original Fallout games.
Like the original title, the player was restricted to only picking from a range of per-created potential protagonist characters, each having a respective skill set.
In addition to a new stealth system, the game incorporated a reputation system that would dictate the progression of the story based on the player's choice of morality throughout their playthrough.
"Stage Bosses" would've have been battled to mark the end of every segment of the game.
An observation by ProgrammingAce of the Game Of The Art forum, who leaked the design document by Brian Freyermuth, is that the predecessor was merely a source of funds for the sequel, hence its poor quality. 
The game's development began before the original title, allowing for the Dark Alliance engine, which had been used for the original, to be revised. Quest structure would've been designed reminiscent of the style of the original Fallout. Like many games of the franchise, the game's style drew influence from the Mad Max series and films from the 1950s.
The game was canceled when Interplay laid off the majority of their employees. The game was never publicly announced.
The design document for the game was leaked in 2009, constituting almost all of the available information, filled with in-game photographs. Minus page 5, the entirety of the document is available. No gameplay footage has surfaced.