Xenophile said:
For the sake of arguement, let's say Fallout 3 follows the core tenents of an RPG (Consequences, character skill determinate in outcome, etc.), and it carries the world created from original Fallouts. (I understand you probably don't agree on the above points)
What specificly do you think it would still lack that would prevent it from being called a sequel?
This is a rather narrow view of RPGs you have.
RPG isn't this one, narrowly defined genre of which all games follow on specific design set. RPG is an umbrella term, ranging from action RPGs to traditional RPGs as you describe. One is not more RPG than the other, it's just a matter of preference.
Anyway, if Fallout remains true to the small, core definition of the originals, that is to say a retro-50s post-apocalyptic pen and paper emulation, then it'd be a true sequel. Details aside, all of the setting details emerge from the being retro-50s post-apocalyptic and all of the gameplay details (choice and consequence, turn-based combat) emerge from it being a pen and paper emulation.
Details would still be hammered on, as was the case for Van Buren, but its status of sequel would not be in much doubt. Interestingly enough, the status of Van Buren as a sequel to Fallout 3 was never in doubt, despite the fact that it had both TB and RT (hell to balance). Why? Because it was designed from the philosophy of pen and paper emulation outwards. If you start there, you can't help but pick up TB combat along the way, and RT combat being tagged on hurts the balance of your game but doesn't change the fact that your intention is like that of the originals.
It's a bit of an academic question tho', isn't it?
EDIT: also, you could seriously mess up and just make a shitty game despite having the right starting principles, I guess