Welcome to Sudoku, the Japanese number game that will have you puzzling for hours. The rules of the game are simple: Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9 without repetition. Solving time is typically from 10 to 30 minutes, depending on your skill and experience. You will be given a random puzzle and there is one and only one solution.