Zobrist cubes are similar to the classic "Soma Cube" puzzle, except that there are many more 3d shapes having sizes up to 5 small cubes. There are enough pieces in the set to simultaneously construct 5 3×3×3 cubes. The set comes with a code book containing thousands of codes, each of which specifies a set of pieces from which a 3×3×3 cube can be constructed. The competitive version is to race another player to construct a cube with similar difficulty, but different pieces.