Let me start by saying your post doesn't really make any sence. I'll try my best to answer your problem.
Fog probably refers to fog in the game. It's a special effect that you can switch on and off in the configurator. It doesn't change the game, but with fog, the game looks a bit nicer and runs a bit slower. (Unless you have a decent computer)
Smooth (altough I haven't tried it myself) should probably refer to performance, and not image quality. It would only make more sence that way. Smooth is therefor probably used to make animation look smoother, when your computer can't handle the game fully. Instead of dropping frames, your computer will try to smooth out the animation, which results into a slow-motion type of thing. That's my best bet.
Not sure what alpha bit is. All I know about that is that if the game isn't running properly, turning it off might help.
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