Fixes a lot of the engine-related issues of the original Morrowind, and also allows for multiplayer fuckery thanks to the TES3MP mod. There's nothing like arriving in Gnisis by silt strider only to realize that the silt strider guy there is dead because every NPC in the overworld is loaded in if even one player is outside, meaning that they wander around and mostly die of fall damage or fall into bodies of water before you even find them.