Are regular sudokus starting to seem too easy? At 21 feet, 9 3¼4 inches long, and with 8,929 empty squares to fill, this huge puzzle adds big excitement to the popular game. It’s composed of 167 regular-sized (9x9) sudoku puzzles, linked together at 3x3 corners. Among the noteworthy features here: each individual puzzle’s starting numbers are symmetrically placed in the puzzle, and no more than 30 numbers are given. Also, each 9x9 puzzle has a unique solution: no two are alike. And, finally, the difficulty level increases as you progress from left to right, becoming quite formidable by the end.