Have fun all you want with Fakeout three. As for just a different play style, no, not even close. They totally changed what the universe was about. For example, the Brotherhood of Steel was NOT a crusading organization. They were secretive, small, and technology hoarding. Not out to save the wastelands as Fakeout three changed them into.
And they addressed that in-game with the scism of the Brotherhood. A lot of the Brotherhood members disagreed with Elder Lyon's plan to save the Capital Wasteland and took a bunch of weapons and armor and left to continue their mission of salvaging technology. They became the Brotherhood Outcasts because while the Brotherhood disagreed with Lyon's decision and cut off support, they still recognized him as the leader of the DC chapter.
I actually think it was a good plot device as it makes the Brotherhood seem more like a real human society, with dissenters and it's own internal struggles instead of a monolithic collective where everyone thinks and believes the exact same thing.