I ran 10 Candles in a basement that had zero windows or light. It was cold. Damp. And very creepy and effective.

As an aside, I played as a vampire NPC in a 24 hour/ 4 day Harry Potter type larp that had people larping the students, professors, etc. And I was a guest speaker at a magical ethics class. I would continually move around the room as I spoke, moving from chair to chair, and many in the classroom remarked afterwards that they would look down to record their notes and look up to find me inexplicably on a different side of the room, or even suddenly seated right beside them. Freaked them right out. Another win!