One card is the key, the one key. The players have to find him by following the advice of the whistleblower. But which card out of the eleven randomly laid out is the right one? In One Key is a collaborative experience that combines creativity, ideas, and associations with beautifully illustrated and uniquely shaped cards. The clue giver uses clue cards to show how strong the connection between these cards and the key is. The seekers now have to remove cards that they believe are not the key. If the key is the last remaining exploration card at the end of the last round, the entire team wins. One Key is a cooperative guessing pass that makes your heads smoke every round.