The following functions are supported:

The top buttons:

New For creating a new game with selected difficulty - click here.
Level Set your desired level of difficulty before creating a new game.
Enter Use this button when you want to enter a game from a newspaper or a book.
About This help screen can be displayed by using this button.
Exit For terminating the program. If you have an unsolved puzzle, you'll be prompted for saving.

Info show/hide buttons:

The info panel is shown by clicking this button.
The info panel is hidden by clicking this button.

The help buttons to the left:

3-box digit Any three horizontal boxes must have a certain digit on different rows, and three vertical boxes must have a certain digit in different columns.
Row digit Find a row with a cell where a single digit is possible.
Column digit Find a column with a cell where a single digit is possible.
Box digit Find a box with a cell where a single digit is possible.
Cell digit Find a cell where a single digit is possible.
Lists Enter/leave "List mode" in which all empty cells contain a list of all digits that are still possible there.
Cell solution Reveal the correct digit for this cell.
Game solution When you - or this program - cannot find the correct solution to this puzzle in a controlled way, you can always get it here.

The navigation buttons:

Restart If you want to restart your puzzle from the beginning.
Backward To regret setting a digit - use Forward or Resume to un-regret.
Mark If you want to try uncertain digits, you can mark this position and return to it later with the Go mark-button.
Go mark Return to the previous position marked with the button above.
Forward Remake settings after using the Backward-button.
Resume Resume the last position after having stepped backward.

Playing the game

When selecting a cell, you can either use the keyboard arrows or use the mouse. And for entering a digit in that cell, you have three choices: Removing a cell digit is done either by using the keyboard space bar, or by right-clicking the cell and choosing 'X' from the popup-list.

The number buttons can also be very helpful in showing patterns. In ordinary play mode when you mouse-over a number button, it will highlight all cells containing that digit.

List mode

When entering a digit that is already on the list, that digit will be removed from the list for that cell. Exception: When there is only one digit left, it will be entered as the value for that cell when you press it. When moving the mouse over the digit buttons in this mode, all cells where that digit is included in the list will be highlighted.

Below the puzzle you have a couple of buttons that are really helpful:

   The reduce buttons can offer you quite advanced help with the more difficult puzzles. The following strategies are implemented:
   This button rebuilds the lists of possible digits in all cells.

Notes:
Right-clicking the background image will show it without any disturbing buttons or boards.

In the statistics window you can also right-click the background to see it clean.