Supply players with a lantern that's almost out of oil or a flash...

Supply players with a lantern that's almost out of oil or a flashlight with dying batteries. Require them to make it into another room before they run out of light. [Note: If they do run out of light, you have the option of forcing them to forfeit the game or allowing them to continue to play in the dark, perhaps with a sliver of light seeping in through a "window." Or you can tell them they've been eaten by a grue.]