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As title says...what MMO has or had the most unique world? A world not seen in movies, nor seen in any games. A world filled with things not found in other games...dragons...orcs...elves...nearly every fantasy game and books have those.
My list (no particular order)
1. Asheron's Call. Not a single thing was taken from fantasy (well no fantasy I know of)...all unique. Every monster in the game was found (and still is not) in any other game, MMO or singleplayer. No dragons, orcs, elves or any of that typical fantasy.
2. Ryzom. Like Asheron's Call...and maybe even more so...this world is very unique. And it isn't just because the animals and races and lore are unique. But the world itself is...the inhabitants live on a giant plant...on top of that...it has very unique environment mechanics . Herbivores go up to you, examine you, pee on you, cower before you...carnivores attack the herbivores...herbivores gather into groups and defend themselves against said carnivores...and animals migrate. Never seen any other MMO do that.
Now, I never played Anarchy Online...and while it was the first MMO to do an actual sci-fi world...I'm not sure if it truly is unique in the game world (mmo or not). I never got into it (was still into AC). However, I'll put it down...since a sci-fi alien world, is rather unique in the MMO world. And sci-fi games in general, tend to be really unique.
I'm sure there are more...but a quick scan through the game forums list, and nothing pops out at me. So, feel free to share your experiences with unique MMO game worlds. That being, ones not found in any other game. Bonus points if the game doesn't take everything from a book...which isn't very unique really. Still, if it does come from a book...no harm in that...unless it has dragons, orcs, elves and all that jazz, since that definitely makes it not unique :P