Sudoku Hard. Daily Sudoku Challenge. Every day three sudoku puzzles with easy, medium or hard difficulty levels to choose from. The objective of the sudoku game is to complete the board by placing in each empty cell a number from 1 to 9. The choice of each number is not random, but must respect three basic rules: there cannot be repeated numbers or in the same row, neither in the same column, nor in each of the 9 grid regions formed by 9 cells (3x3) into which the sudoku game board is divided. Sudoku is played by applying logic, placing those numbers that cannot be placed in more than one cell. Accept the challenge and complete the sudoku game.