I'd rather not bother, XIII didn't do much to make me like the world and its wacky fantasy/sci-fi hijinxs so I don't see the point of trying to do it again.

I just don't see any interesting plot elements that could go in its world without making it a prequels or sequels set a 1000 years away from the main game. Even then, I feel it would suffer a bit of most SE sequels and feel like a minor re-telling of the original game. I say we just leave this one behind.