It would be relatively easy to do, as he said, we already have the possibility to make dark maps (see hunt mod), Torches with Light 8Hunt mod too), guards patrolling (Well, depends on the palyers), and half visible people (Ghosts in Race Wars Bloodshed)
But I won't be doing it, this is, if I understand it right, what the guy from "Cloak and Dagger" wants to do (if he is still active, I don't htink he is)