Fog ! (have u seen Carpenter's "The Fog" ?) Visibility turn to only few tiles (map vanishes). Physic nidbanes stalking wanderers out the fog and wrecks ships in see. Only high psyche and will allows doomed travelers to escape.
How about a new wound from a Carpenter movie? "Infected by The Thing." The more people you can infect before you die, the more recovery you can get on your next character.
Fog would be a great addition, but I guess it has the same problems as the lighting suggestions in caves.