I would say that the mist isn't a good idea, at least to me.
I really like the game, but I have played games that use low visibility to enhance difficulty.
(a game called GTFO) I Don't dislike that game either.

But using it as a mechanic does mean people with eye troubles will have to play it less.
I'm lucky enough to not have such problems but some friends of mine said with GTFO it gave them headaches and generally was uncomfortable after a while because of the fog.

Which they will probably have similar issues with the mistlands.