The Sudoku application allows both solving problems as far as generating new ones. The application supports both normal classic 9*9 Sudokus and X-Sudokus (also with an edge length of nine). The use of the Sudoku program is completely self-describing: Select simply a field with the keyboard or the mouse and enter the desired number. This also could be done using the mouse: Turning the mouse-wheel upwards increases the value, downwards decreases the value in the cell. And if you have made a mistake: Just undo the last input and try again. When solving the problem interactively it is possible to mark "candidates" for cells. The language of the user interface of the application can either be English or German. It is possible to save problems and reload them later. Problems can be printed out with or without their solutions. It is also possible to generate "Booklets" with a definable number of problems (an example can be downloaded). These booklets can either contain newly generated problems or existing problems generated in advance. All newly generated booklet-problems are by default automatically stored in a definable directory (see "Other Options"). When solving a problem interactively you can either check the validity of the problem on demand (by pressing <F7>) or set the "Auto Check" option. In the latter case, the application automatically gives you a hint, if the entered number leads to an unresolvable problem. If you need help, the application can give you hints by pressing <Ctrl-F1>. This feature marks those cells, in which only one number can be entered and the problem remains valid. The problem can always be automatically solved by pressing <F4>. If the corresponding option is checked, this can be tracked. Another option lets you define whether or not all possible solutions for a given allocation should be found. (Certainly, an allocation with more than one solution is not a valid Sudoku problem, however, these allocations are not rejected from being solved. BTW: The empty Sudoku problem has roundabout 6.7*1021 solutions...) Pressing <F8> shows an info box about the current problem, including a "Severity Level" ("trivial", "easy", "intermediate", and "hard"). Another nice feature of the Sudoku application is the possibility to set the option that an indicator of the possible values of each cell can be showed and/or be printed out either using digits or "watch hands". For detailed information about the "Sudoku" game, please refer to this article.