Sudoku is a game of pure logical deduction, where no guessing is ever required in the puzzle game. Hard Sudoku may test your belief in this, but just stick to logic, and you are sure to power your way through to an ultimate Hard Sudoku win! Sudoku game play is the same as all other difficulties on 24/7 Sudoku. Place the numbers 1 through 9 into each row, 3x3 box, and column only once. Complete the entire sudoku puzzle with the correct numbers to win. Hard Sudoku differs from easier difficulties, in that there can be multiple spaces where the answer is not immediately obvious. This level of sudoku difficulty may require you to use more complex ways of solving, not just simple logic like you've used in both Easy and Medium difficulties. These advanced sudoku techniques most times involve discovering patterns in your sudoku board. Remember, no guess work is involved in this logical game, so just keep trying, and you're sure to become a victorious Hard Sudoku master!