Unown are creepy enough on their own. Then you have the sheer numbers of them, which are better suited for collecting. Pair these things with the impossibly unsettling radio signal from the Pokegear radio, and you've got yourself a veritable recipe for nightmare fuel. The dark ruins are rife with secrets and hidden rooms, acting as such a parallel to the normal goings-on in the Pokemon world that when you leave to encounter daylight again, it all seems like you just stepped out of a dream.