Sudoku Hard. Daily Killer Sudoku. Three levels of difficulty, 3 board sizes, 6 different calcudokus every day of the year. The objective of the sudoku game is to complete the board by placing a number from 1 to 9 in each empty cell. The choice of each number is not random, but must always 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. A fourth rule is applied to this type of sudoku and that is that the numbers to be placed in each randomly drawn section add together the result indicated and without using repeated numbers. Sudoku is played by applying logic, placing those numbers that cannot be placed in more than one cell. Accept the challenge and complete the game of calcudoku.