Earlier products from Mad Cave Bird Games include ColorKu and Tic-Tac-Ku. ColorKu is Sudoku translated from numbers to colors and made with wood pieces. Obviously, it’s not convenient for the commute, but for some reason it makes this common puzzle much more attractive, to me at least. Tic-Tac-Ku is based on Tic-Tac-Toe but is played simultaneously in nine zones. It won a Mensa Select award in 2009.

Mad Cave Bird’s latest game is 22 Ku-du, which includes 108 single-digit numbered wood tiles and challenges players to build crossword-like rows and columns with equations that result in 22. The game is scalable in that you can play using just addition and subtraction, or you can allow any combination of functions.