Stuck in an underground labyrinth where you could walk on the walls or ceiling so long as one foot was planted on the floor at a time. Blood everything, no lights, absolute darkness. You meet people on the way who are nice, they talk, they socialize. Then they are claimed by some horrible invisible beast that rips them up. No weapons to fight with, nothing at all. Only can run. You only know that the monster is close because you see it kill somebody. I hate it how my rare nightmares are never lucid.