Moving your mouse around the board you'll discover a gray
grid of numbers appears over each open square. Simply click
one of the numbers to mark it as possible for that square,
click it again to unmark as possible. To choose the
square's value double-click the number. Double-click the
square again to clear the value. With the keyboard
<Ctrl> plus the number will mark/unmark a possible
and typing the number will enter a value. <Delete>
will clear a value. There is full Undo/Redo support for any
mistakes you might make!
There are three levels of puzzle difficulty and you may
also enter your own puzzles from your favorite newspaper,
book, or Internet puzzle source. You may save any puzzle to
finish later or print a puzzle out at any stage to finish
by hand. In the preferences screen you may choose your
default puzzle level and also disable the timer.