SudoKoach™

Overview

SudoKoach is a Windows program that makes solving Sudoku puzzles more fun by doing the tedious work for you. It also gives you hints and tips that can help make you a better Sudoku player. (What is Sudoku, anyway?)

New players: Learn strategies to solve more challenging puzzles.
Puzzle addicts: Create as many puzzles as you like in six levels of difficulty.
Web addicts: Play our Sudoku puzzle of the day on our web site.
Publishers: Read about how you can use SudoKoach to create puzzles for your publication.

Details

When solving Sudoku puzzles by hand, you eventually reach a point where you have to figure out what numbers are possible in each unsolved cell. While this task isn't difficult, it is time-consuming and error-prone, so it isn't much fun. SudoKoach does this work for you, so you can get right to the more interesting and challenging aspects of solving the puzzle.

SudoKoach doesn't solve the puzzle for you. In fact, the only work that it does is work that you can do yourself (but isn't much fun to do).

Solving Sudoku puzzles with SudoKoach is more fun because:

You don't have to figure out which numbers are possible in each cell.
There is no need to write down and constantly update these possibilities.
You can check any time to see whether you've made any mistakes.
If you make a mistake you can easily undo your moves.
You can resize the window to make the grid as large as you want--no more squinting!
If you get stuck, you can get hints to get you going again.
You can create as many puzzles as you want, with six different levels of difficulty.
You can enter puzzles you've found elsewhere and solve them too.
You can print puzzles (with or without showing the possibilities) for later solving, or to give to friends.
You can practice any of the solving strategies to improve your skill.

Purchase SudoKoach for a lifetime of solving fun!

Runs on

Windows 95/98/NT4/2000/me/XP, and all versions of Vista.

Price

US$12.95 for one computer; $2.50 for each additional computer. Shipping/Handling: FREE if you choose delivery by email OR are in North America, $3.00 otherwise. Discounts may apply--see the order form for details.

SudoKoach can be delivered by e-mail. Or we can mail you a CD-ROM--this can serve as a backup in case you ever need to reinstall SudoKoach later. The CD has simple point-and-click installation and includes additional shareware and other software that is too large to send via email.

Revision status

The current version is 2.1. Read a list of the new features in this version. Registered users of 2.0 can download a free update to 2.1.

Registered users of version 1.0 or later can also download a free update to 2.1.

Detailed description

When SudoKoach displays a Sudoku puzzle, it shows you which numbers are possible in each unsolved cell, like this:

The large numbers indicate cells that have already been solved; the other cells contain smaller numbers that indicate which values are possible. With this information, you can immediately start looking for the more interesting patterns. Here is an example:

In row one, there are two cells that can only be 8 or 9.
One of these cells must contain the 8, and the other must contain the 9 (though we don't know yet which is which).
8 and 9 therefore cannot appear in any other cells in this row, as they've already been used.
This means that cell 1,2 (that's row 1, column 2) must be 6.
Cell 1,5 must therefore be 4.

Solving cells and eliminating possibilities

Solving cells and eliminating possibilities are the two tasks you do most often in SudoKoach. Therefore, they are extremely easy to do.

To solve a cell, just point the mouse at the possibility you think is the answer and left-click it.
To eliminate a possibility from a cell, just point the mouse at the possibility and right-click it.

Undoing mistakes

If you find that a cell has no possibilities, you must have made a mistake somewhere along the way. To fix this, simply undo as many of your moves as needed to remove the problem. You can check as often as you like to see whether your moves so far have been correct.

Highlighting

Many cells are solved by observing that they contain a possibility that cannot appear in any other cell in the row, column, or 3x3 box. SudoKoach simplifies this search with a feature called Highlighting. When you highlight a value, all unsolved cells that contain the value as a possibility are shaded so that they are easily visible.

In the puzzle below, the value 5 has been highlighted. Just look across each row, down each column, and in each 3x3 box--if you find exactly one highlighted cell, then that cell must be a 5:

Highlighting makes it easy to spot these solutions:

Cell 4,9 must be 5 because it is the only one in column nine in which 5 is possible.
Cell 7,8 must be 5 because it is the only one in row seven (and box nine) in which 5 is possible.

Clues and hints

If you get stuck solving a puzzle, you can ask for a hint. A big hint either solves a cell or removes possibilities from one or more cells. In either case, the hint will explain the logic behind the suggested move. The hint below describes a box in which only one cell can contain the value 4 (a "hidden single").:

If you need a hint but don't want to be given an answer, ask for a "little hint"--this will tell you what to look for next. In the puzzle above, a little hint would have told you: "Look for a hidden single."

A "medium hint" is like a little hint but also tells you the number to look for. In the puzzle above, a medium hint would have told you: "Look for a hidden single with the value 4."

Practice mode

Learning a new strategy is easier if you are able to practice it. For this reason, SudoKoach has a practice mode. You select a strategy, and SudoKoach will generate a puzzle in which the chosen strategy is the next move. This makes learning the strategies a lot faster.

Also, the help file tells you the frequency with which each of the strategies appears in puzzles. This is particularly helpful when choosing which strategy to learn: start with the more common strategies, and learn the less common strategies later.

Making the puzzle larger and smaller

To change the size of the puzzle, just resize the window. The digits automatically change size to fit the size of the puzzle.

Entering your own puzzles

You can also solve puzzles from books or newspapers with SudoKoach. After you've entered the puzzle, SudoKoach checks it to verify that the puzzle has exactly one solution. Then you can solve the puzzle exactly the same as if SudoKoach had created it for you.

Printing puzzles

You can print puzzles to solve when you're away from your computer, or print puzzles you've created for your friends to solve!

Why not try it out for yourself?

It's a lot more fun to play SudoKoach than it is to read about it! Why not download the shareware version and try it out?