The fog is likely grease, it will happen if you cook at home. Gently run your finger on the surface of the game and see if your finger feel greasy. My game collection (the old ones that don't get played) are stored in my study. The room has ceiling light with clear glass cover. I can see the glass fog up after a year or so, even when the door of the room is closed most of the time, and I rarely cook at home. Funny you mention Windex, because that's what I used to clean that light cover.
For the PS2 and Xbox seals, if they seal is not the stretchy type, it should be safe to clean them with Windex, but instead of spraying on the game, you spray on paper towel, or micro fiber material then rub it gently. Try it on a cheap game and see how it goes.