Sudoku 42

Put values to the sudoku game field one by one, two players each at its turn. Select a field first and then the value to be put. The CPU will do three checks: 1. Is it not yet used in its row, colum or square? 2. Will this field be needed for another value, which has no other place to which it can be put within this square? 3. Can the CPU still solve the sudoku riddle to the very end? If all three checks complete successfully, the value is put your draw extended. Extension means, that the CPU fills all fields for the current player where the value has become unique by the last put. And that may be many fields, at the end of the game. The game ends, when all fields are filled. Winner is the player with the most fields.