I will probably use the fog thing you suggested. :) I just mean that being in the extreme darkness is part of the gameplay. One player has a flashlight, one has a gun. The two are supposed to need each other. The flashlight will stagger enemies so the other player can shoot them. I just mean that the flashlight will be extremely important to the player, and the story.
RE: Lock In's new title screen might evoke a familiar feeling (gameplay screenshots too)