September 20, 2015 3:19 PM EDT
I feel like I should say Middle Earth but there are so many out there.
Probably the Ebberon D&D setting as it is very unique and almost alien to any other world I have played in before. Nirn is great because of its complexity in lore and I like how it has a nice balance between gritty realism and being very whimsical and high fantasy like at other times.