Quick notes

Just a few quick notes as I'm busy doing other stuff to write this guide up.
The applet is (should be) intuitive enough to create and play Su Doku problems straight from the newspaper. Just open it up and have a bash.

Position A unique board location
Fixed Make a position non-modifiable
Group A row, column or grid
Grid An inner box of values
Value Typically the numbers from 1 to 9 inclusive
RMB Right Mouse Button
MMB Middle Mouse Button (where available)
Placement cycle

Unlike other programs, you keep clicking (left mouse button) on the same square to get it to change to a different value (or none at all). What values appear will depend upon some of the options you may have selected (i.e. Placement Assist). Some positions will not be changeable (aka fixed, non-modifiable) and have a grey background.

Focus issues

Seeing as a web browser hosts this applet and requires its own handling of the keyboard and mouse, things can go awry. If you're having troubles with getting key presses to work, click about outside the playing area (but within the applet) and try again.


Here things get weird.
As a preference over pencil-marks (candidate drawing) and from playing Rays from Hoyle Puzzle Games 2005, I've implemented a flagging/highlighting system. When playing on good ol' pen and paper, using your finger is handy to mark or discard a group. Here I've emulated this with a saturated yellow background when you use these keys:

Arrows Highlight the position from where the pointer rests in the direction of the arrow
Shift Clear all highlights
Enter Highlight the grid under the pointer
Ctrl Highlight all intersecting rows, columns and grids
RMB or MMB Toggle the highlight under the pointer

Now, if you do like pencil-marks, you may enable them via the Action menu.

1, 2, ..., 0 Remove the specified candidate in the position from where the pointer rests
Backspace Remove candidate changes in the position from where the pointer rests