Perhaps the hardest part about writing an Adventure Game. It's like this: Suppose you're writing a Noir-styled game, and you decide that a good puzzle would be to have our hero offer his lighter to the classy dame as a way to break the ice. The puzzle hinges on the player picking up clues from the genre and environment to determine that this would be a wise course of action, and that he actually find his lighter, which could, in turn, require that he find the key to his desk drawer, where he keeps it, and so on and so forth. Reasonable puzzle.