Sudoku Rax Help version 1.0

1. General

Sudoku Rax is a MS Windows program for playing the number puzzle Sudoku.

Features:

· Enter and edit puzzles with the mouse and/ or keyboard,

· Display the puzzle in varying size (small to full screen),

· Generate random puzzles with different difficulty levels,

· Load and save puzzles from/ to disk,

· Print a puzzle on a Windows OS printer,

· Help for solving puzzles with hints in varying depth (showing legal digits, fields with only 1 or 2 legal digits, illegal fields, …)

· Undo/ Redo function for tried digits

· Accept/ clear "tried" digits

· Support for solving puzzles with "scratch digits" (markers for legal digits in a field)

· Statistic windows

· Help (general help file, status bar, tool tips, …)

2. Rules of Sudoku

The Soduku square board (grid) consists of 9 x 9 = 81 fields which can be seen as 9 columns , 9 rows and 9 3 x 3 sub squares ("F9 region"). The aim of the game is to put a digit between 1 and 9 in each empty field of the board with the condition that every row, column and F9 region contains no double entry. In other words every row, column and F9 region must contain the digits 1, 2, 3, 4, 5, 6, 7, 8 and 9, no number missing and no number twice.
The game starts with a board ("puzzle") with certain fields containing "fixed" digits, called "givens". The player has to solve the puzzle by filling the empty fields, obeying the above defined rule, until the board is fully

3. User Interface

Sudoku Rax consists of 6 windows

1. Main window
- displays the Sudoku panel, the main menu, a toolbar and a status bar

2. Options window
- dialog window for entering options like difficulty level, …

3. Statistic window
- displays statistic data of the current puzzle

4. General help window
- shows general help information (this file)

5. Registration window
- displays copy right info and is for input of the registration key code for Sudoku Rax

6. About window
- displays author and version info and state of registration

Message dialogs and the status bar in the main window inform about the progress, state or error conditions of the program.
When using the program for the first time it may be helpful to check the check box "Inform extensively about changes with a message box" in the Options dialog window, which displays additional information.

3.1 Modes of play

Sudoku Rax has two independent modes, edit mode and help mode, which control the display and entering of data.
The modes can be toggled on/off with the help of the tool bar or main menu.
The actual statuses (edit on/off; help on/off) are displayed in the status bar on the lower edge of the main window.

Edit mode "on" is meant for creating puzzles by entering digits.
With Edit mode "on" all fields in a puzzle can be edited (filled, changed, emptied). Entered digits are stored as "givens".

Edit mode "off" is meant for solving the puzzle. Fields with "givens" may not be changed. Entered digits are stored as "tries".
"Tried digits" may be changed again, cleared or accepted.

3.2 Entering digits

Digits (1-9) are entered into the fields of the Sudoku puzzle in the main window with the keyboard or mouse.

Initially no field in the puzzle is selected. After selecting a field with the keyboard or mouse (see below) the field is hatched light red and a digit may be entered or changed.
Press the escape key or click outside of the board grid with the mouse to unselect a field.

Input by keyboard:

- select a field with the cursor keys (left, right, up, down, home, end, TAB, Shift/TAB)

- input digit (1 – 9, blank or 0 for empty field)

Input by mouse:

· Select a field by clicking with the left mouse button inside the field area

· Press the left mouse button over a already selected field to open a context menu

· Choose a digit (1 – 9 or Empty) from the popup context menu with the mouse

Remarks when "edit mode is off":

· While holding down the right mouse button over a "given" digit every appearance of this digit in the whole grid is highlighted yellow;

· Scratch digits may be entered into a field by pressing the right mouse button over a selected field (see also 3.4.3);

3.3 Create/ load a puzzle

A new Sudoku puzzle may created

- By hand, entering the given numbers in edit mode:
Clear the board with menu "Puzzle/Clear puzzle". Enter the digits with keyboard or mouse. Save the ready Sudoku puzzle to disk with menu "Puzzle/Save puzzle as …"

- Automatically by random generation:
Choose a difficulty level (easy, medium, hard, user defined) for the puzzle with menu "Options" in the Options dialog window (level radio buttons). Start the random generation with menu "Puzzle/generate puzzle" or click the shortcut in the toolbar. Please be patient and watch the busy cursor as the program needs some seconds for several tries to generate a valid puzzle.

Or load an existing puzzle from disk with menu "Puzzle/Load puzzle …" .

Puzzle file format:
Sudoku Rax writes and loads puzzle files with the default file extension ".sdk" or ".txt", but tries also to read/ load files with other file extensions.
By default Sudoku Rax expects a text file which contains 9 lines with 9 characters (numbers "1" – "9" resp. "0"/"blank" for an empty field), so you may create/edit a puzzle by yourself with a text editor.

3.4 Solve a puzzle

3.4.1 General

A puzzle is solved by entering digits in the empty fields of the main board until all 81 fields are filled. If the full board is valid, a dialog message congratulates you for successful solving. If the puzzle is invalid, a dialog message informs you about this fact.
At every stage of solving you may check the puzzle for validity with menu "Puzzle/Validate puzzle" or the corresponding shortcut in the tool bar.

In the progress of solving it is recommended to save regularly the changed board to disk with menu "Puzzle/Save" or toolbar shortcut with the current file name or with a new file name (menu "Puzzle/Save as …").

Help in varying degree may be used by turning on the "Help mode" (see below).

With menu "Solution/ Auto Solve" the puzzle is instantly solved by the program or an error message is displayed if the puzzle is invalid.
With menu "Solution/Unsolve" or the corresponding shortcut the original state of the puzzle before auto solving is restored.

3.4.2 Do/ Undo feature

Entered "try" digits are colored differently from givens and stored in a history stack and you can redo/ undo "tried digits" with forward/ backward navigation buttons at the bottom of the main window.
If you are "sure" with the entered digits you may accept the tries (menu "Solution/Accept tried entries"). Or you may discard your entries so far with menu "Solution/Clear tried entries".

3.4.3 Scratch digits

A very useful help for solving a Sudoku is to pencil down in a field the remaining legal digits which are still allowed to be entered in this field.

In every (empty) field of the board up until 9 "scratch digits" (1 – 9) may be inputted by the user with a context menu after pressing the right mouse button. The digits are not validated for correctness by the program, even with help mode on.
All scratch digits are displayed as small numbers in the empty fields of the board. The display may be toggled on/off with menu "View"/Show scratch digits".
All scratch digits are cleared with menu "Solution/Clear all scratch digits".

3.4.4 Highlight surrounding of selected field

A sometimes useful feature for solving is to highlight all (20) cells which belong logically to the neighborhood (surrounding) of the selected field (same row, same column, same 3x3 region).
This feature is toggled on/of with menu "View/Highlight row/column/3x3 field of selected index".

3.4.4 Help features with Help mode on

The following help features for solving a puzzle are individually toggled on/off with "View" menu items, but the switched on help information is generally seen only when the Help mode is on.

Mark illegal fields:
When turned on (menu "View/Mark illegal fields") , fields which are illegal (contain an illegal digit or an empty field with no possible legal digit) are framed red.

Show legal digits:
When turned on (menu "View/Show legal digits in empty fields") , all legal digits in the fields are displayed as small green numbers.
Attention: There is a check box in the Options dialog window " If in a field is only 1 legal digit do not show the digit legal in the surrounding (adjacent row, col and F9 region". If this check box is checked, fewer "legal digits" are displayed because of this more stringent constraints.

Mark fields with only few (1,2,3) legal digits

When turned on (menu "View/Mark fields with only x legal digits"; x = 1,2,3) , fields where only x legal digits are left possibly for enter are framed with a color rectangle (1 = green, 2 = yellow, 3 = cyan).
Attention: see also the attention remark in the paragraph above.

3.5 Print a puzzle

Menu "Puzzle/Print" opens a printer dialog box. Choose your printer and set up your printer (paper format, print quality, …).
Sudoku Rax prints the current view of the puzzle as seen on the screen in color, fitting the Sudoku grid to the paper format.
Be sure to display the puzzle on the screen in the form you want have it printed (e.g. toggle help modus on/off before printing).

4. Copy Right and Registration

Sudoku Rax version 1.0 (c) 1.5.2006 is Shareware. You may download freely an evaluation copy from http://www.rdchess.com.
If you use the program more than for evaluation I expect you to pay for its use.
The price is $ 7.95 and includes the right for free updates to newer program versions.

To register the program please open with menu "Help/ Register Sudoku Rax" the registration dialog box and enter your registration key.

5. System requirements

Sudoku Rax runs on Personal computer with MS Windows XP and uses the .NET runtime environment.

Main memory demand ca. 500 kB. Processor speed > 500 MHz recommended. Hard disk space approximately 2 MByte.
Sudoku Rax runs also under Windows 98/ME, Windows NT4, Windows 2000, if the .NET Framework Version 1.1 Redistributable Package" is installed. This package can be installed with the Windows Update function or downloaded from www.microsoft.com/downloads and installed manually.

6. Installation

Sudoku Rax is delivered as self extracting .exe file "Sudoku Rax Setup.exe".

Please run "Sudoku Rax Setup.exe" and follow the installation dialog. Sudoku Rax installs per default to the newly created directory "Program Files\Sudoku Rax".

A few example Sudoku puzzles are copied into the directory "Sudoku Rax\Sudoku puzzles".

Sudoku Rax installation creates a program group "Sudoku Rax" and optionally a desktop shortcut.