From the Publishers web site:
In Brief: 22 Ku-du is the wood tile math crossword game that's fun for all ages. Easily adaptable to all skill levels. Make all your rows and columns total 22. Learn while you play. 108 all-wood tiles
In Detail
Each player draws 7 tiles to begin play. Players make crosswords of numbers so that each grouping adds up to 22. As tiles are used to make a "22" a player yells "Ku-Do" and draws more tiles so that they are always working with 7 tiles. Play continues until all tiles are gone. Each "22" scores 1 point. Use of two of the same number in the same equation scores an extra point and three of the same number scores two extra points. Each player checks the other player's crossword and scores if they find any errors.
Many variations of play are left to the player or teams, depending on age or desire. Players can determine the number of rounds for each game, can use dice to set a new "goal" number in each round, or can use the color number tiles as either positive or negative numbers. Many different variations are possible to enhance the game and match the players skill level.