Abstract: This relates to a game which includes a game board and a plurality of playing pieces. The game board is generally rectangular in outline but is provided at one end with a projection which is intended to interlock with another game board. The projection defines at least in part a receptacle for game pieces. The game board at the end thereof remote from the projection has a reserved area for receiving a selected code playing piece of a set of target code playing pieces and a code playing piece of a set of position indicating code playing pieces. The playing pieces also include test playing pieces conforming to the target code playing pieces and marker elements for signalling the correctness in relation to the code playing pieces mounted on a related one of the boards of the characteristics and relative positioning of the test playing pieces of a test group selected by a player.