MUDs are really cool, but for anyone looking for a narrative fantasy experience, my first recommendation is going to be The Elder Scrolls 3: Morrowind, but more specifically the mod scene around that game as well as the OpenMW replacement game engine.

Bethesda’s game was a gem that was full of rich lore, plenty of readying, and very flexible RPG systems (although being a magical glass cannon does tend to be the best build). However, it was also a relatively flawed game (which Bethesda game isn’t?) that the community has expanded and fixed into a juggernaut.

I recommend picking up a mod pack from modding-openmw.com and checking it out. Tamriel Rebuilt is particularly impressive: fans have added a massive bank of new maps, quests, etc.

Something cool about the OpenMW engine is that it supports scripting that exceeds the original engine so that new quests are more rich and dynamic than original ones in the game. They are even starting to expand into custom spell effects (as the original game had a rigid list of spell effects that wasn’t malleable).