Today, travelling by the immensity of the engine scripts, I found this:
void SetFogActive(bool abActive);
Enables\Disables the global fog.
void SetFogColor(float afR, float afG, float afB, float afA);
afR - red value
afG - green value
afB - blue value
afA - alpha value
void SetFogProperties(float afStart, float afEnd, float afFalloffExp, bool abCulling);
afStart - how many meters from the camera should the fog begin
afEnd - how many meters from the camera should the fog reach full thickness
afFalloffExp - the amount by which the thinkness increases
abCulling - whether occlusion culling is active for the fog; this prevents objects behind the fog from being loaded
This could answer to the fog. Damascus, you could make a lot of fog areas and, slowly, making them visible. It requires a lot of scripting, but...