Use the arrow keys or click with the mouse to change which box is selected. To change the number in the selected box, use the spacebar or just type the number you want. It will automatically show you if you make a mistake that you can see (like putting two "4"s in the same row), and will automatically tell you when you win. It checks for winning by the rules of Sudoku instead of matching some predefined "correct" answer, so if there is more than one correct answer it will recognize any of them. You can click on "CHECK" any time to have it check if you have a visible mistake. (When it automatically warns you, it only shows the mistake for a few seconds - after that you might forget.) If you click on CHECK when there are no real mistakes but you have not won yet, it will highlight some squares that you have not filled in yet. If you have made some guesses but it is not working out, you can click RESTART to erase all of the numbers you put in, and start over.
Thanks to Aleynesansonnet for the original game. My changes were mostly just cosmetic - to let you click on squares, show when you make an obvious mistake, etc.
