Abstract: A decoder board for a Sudoku game has a plurality of keys arranged to present a Sudoku game to a player.

Abstract: A Sudoku board game has a receiver board, a decoder board, and pieces. The receiver board has a plurality of receiver holes. The decoder board has a plurality of key holes, and the key holes are arranged to present a Sudoku game to a player. The pieces are insertable first through the receiver holes and then into the key holes. Each of the pieces comprises a top, a key, and a shaft coupled to the top and the key. The keys are arranged to cooperate with the key holes such that only a key matching a key hole can be fully inserted into the key hole and corresponding receiver hole and such that a key not matching a key hole cannot be fully inserted into the key hole and corresponding receiver hole.

Abstract: A game includes first and second boards. The first board is a competitive board permitting players to compete as the players play the game. The second board is distinct from the first board, and the second board is a cooperative board requiring the players to cooperate as the players play the game.