From the box:Each player takes a black (number) and a white (colour) code counter and secretly places them with the colour and number facing him. The first player then places a row of code pegs in row no. 1. The other 3 players must give information about their own hidden code by placing either a black or white key peg in a key hole beside the first players code.The winner is the first player to break the code. - BoardGameGeek