I really love the Fallout series of games and have thought it would be fun to have the brother hood of steel be from one of the earily attempts at colonization, and something goes wrong with the primative warp drive and they end up in an alternate earth- the fallout post appoctalyptic earth. They probably would not be full fledge Space Marines, more closer to a guardsmen with primative power armour. I am currently finishing a DH campaign and just started a DW one so I haven't really had time to develop this Idea, but thought I'd share it incase someone else had simular thoughts.

Fallout power armour wasn't half bad. Users could still do martial arts in it (Fallout 2) and could soak a *lot* of damage, ignoring most bullets. I do like the idea of primitive power armour though. In any case, best of luck with the idea.