Tetrade is a three dimensional boardgame on a triangular board with six holes on each side. Players put spheres in alternate turns and try to occupy the four corners of a tetrahedron with the size of 2,3,4,5 or 6 elements. Three spheres of lower level carry one sphere of higher level. A player succeeding in forming a tetrahedron receives a sphere from the hand of the opponent, so that this player is stalemated at the end of the game.