You are standing outside the entrance to a dark and gloomy cave. If you are anything like me, you have been here many, many times before. It isn’t always the same cave: Once it was a “cave-like opening, somewhat obscured by vegetation,” which led to the mystical Caverns of Quasqueton; another time it was the Wizard’s Mouth, a fissure in the side of an active volcano (“This cave actually seems to breathe, exhaling a cloud of steam and then slowly inhaling, like a man breathing on a cold day”). Once it was a passage from the throne room of Snurre, the Fire Giant King, “extending endlessly under the earth.” Once, memorably, the “cave” was made of metal: it was the outer airlock of a spaceship which had crash-landed in the crags of the Barrier Peaks. You don’t know what lies in that darkness, but you have heard rumors: there are troglodytes, dark elves, a long-dead wizard, terrible creatures, treasure. You are here to learn the truth. So strike a light: you’re going in.