From the instructions:
This interesting new game besides combining dominoes with crossword puzzles adds a joker feature.
Besides being entertaining this fascinating new game will improve your vocabulary and spelling.
'Crossword Domino like dominoes requires the players to take a group of units thrown together by chance and transform them into order and context. Crossword Domino requires that we link together letters and words as is done in a crossword puzzle.
This game allows the players many possibilities of devising problems to be solved and making rules to suit the particular group of players.