sounds like you would be interested in fallout 3
Well. I do like Fallout 3 a lot. but not quite a MMO is it? It be sort of interesting if they made an MMO with the same gameplay as Fallout 3, certainly.
I don't see that happening though. MMO's and fast paced gameplay don't generally mix because of latency issues.
Though I'd prefer (in a MMO's case at least) a space colonization sci-fi for an MMO. Similar to Mass Effect's world. Mainly because it would open up more variety, which is sort of important in a game you spend a large amount of time playing.