The goal of the game is to find the 4 digits of the secret combination of the box. At the beginning of the game each player takes a keychain consisting of 4 keys and memorizes the numbers written on the keys. In turn, the player places on the board, face up, all the keys he can place on one or more doors by respecting the number and the letter written on each lock. He rejects, face down, the keys he could not place and place them on incomplete trousseaux. When all the locks of a door are put, the player who places the key will have the right to look at one of the gears. The first player to discover the 4-digit combination wins. —user summary