Fog

I realized recently that fog, in real life, has exactly the same effect as fog in old games like Morrowind or Might and Magic IX. It adds charm and mystery to things because it hides the fact that the world is repetitive, unsurprising and – hardly exaggerating – uninteresting.

It's an artificial charm, an artificial mystery, of course: because you can't see into the distance, you expect to discover something gradually more beautiful and richer than what the mist actually hides. That said, it doesn't matter. Just as the illusion of freedom is freedom, the illusion of mystery is mystery.