For me, I don't think a traditional MMO system would suit the game. Fallout Online should be a survival situation like DayZ, where your thrown into the game world and forced to find what you can in ruined buildings, and that the player can make the choice of being either a bandit or a hero. As well as this, there should be various factions you can join in the game world. You should be able to be a Raider, to a member of the Enclave. Of course, if you die, you lose everything and have to do it all again.