It doesn't necessarily have to involve Baldur's Gate, as Baldur's Gate 2 didn't. I do believe, however, that the city of Baldur's Gate will likely be included.
Also, I comletely hear ya about the visual fog. I would spend hours getting rid of it too, and then i would get mad when I couldn't get rid of it all because of a hill or something
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The fact that it would take months to scour works against me. I don't have a lot of free time during the school year, so I typically only play long games like this during the summer or Christmas break. There's nothing worse than only being able to play for about an hour or less a day. It's barely enough time to get started.