Sound-encoded valuesExample: A cat meows 3 times (either short and long sounds).
Later, the player has to make 3 binary choices (e.g. yes/no, left/right, or up/down) in a row, where only one of the 8 (23) combinations leads to the solution. He may solve it by trial-and-error, condoning backtracking, or by using the friendly cat's info, which happens to be the correct code.