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Do you want to have more fun with Sudoku?
I can teach you how to solve more interesting puzzles
and make you a Sudoku Master!

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 on advanced solving strategies that will make you a better Sudoku player. (What is Sudoku, anyway?)

  • New players: Learn advanced 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.

SudoKoach makes Sudoku puzzles more fun to solve

When solving all but the simplest 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 hard, it's 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).

In addition, SudoKoach has 36 different solving strategies built into it. These strategies can conquer 99.5% of all Sudoku puzzles!

Solving Sudoku puzzles with SudoKoach is more fun because:

  • You don't have to figure out which numbers are possible in each cell.
  • You can check for mistakes at any time.
  • If you make a mistake you can easily undo your moves (try that with paper-and-pencil solving!).
  • You can make the grid as big as you want--no more squinting!
  • If you get stuck, you can get hints to get you going again.

Plus, you can:

  • Create as many puzzles as you want, with six different levels of difficulty.
  • Enter puzzles you've found elsewhere and solve them too.
  • Practice any of the 36 solving strategies to improve your skill and become a Sudoku master.
  • Print puzzles (with or without showing the possibilities) for later solving, or to give to friends.

Click the button below to download the 30-day free trial of SudoKoach to see how much more fun Sudoku puzzles can be!

  • If you order within the first 10 days of your free trial you'll get a 10% discount!

"I have the program installed and it is AWESOME! I like it as a teaching tool and also for problem-solving. I'll be honest with you--I have quite a few sudoku programs on my computer and also handheld games, and your SudoKoach is THE BEST! Thanks!"  David R.

Order SudoKoach Now! Download the free trial now!

Runs on

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


US$12.95 for one computer; $2.50 for each additional computer. You will be able to download SudoKoach immediately after placing your order.

For an additional US$5.00 we will mail you a CD-ROM (there is a $3 shipping charge for this if you are not in North America). The CD has simple point-and-click installation and includes additional shareware and other software that is too big to send via download. The CD also serves as a backup in case you ever need to reinstall SudoKoach.

Revision status

The current version is 2.3. Read a list of the new features in this version. Registered users of 2.0 and later can download a free update to 2.3.

Registered users of version 1.0 or later can also download a free update to 2.3.

Detailed description

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

The big 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.

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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 strategy called XY-wing:

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 an XY-wing."

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 an XY-wing with the value 1."


SudoKoach provides coloring, a powerful tool to help you find moves. Here is an example:

We are trying to decide whether cell 2,2 should be 3, so we color it green (to indicate "3"). We then color the cells that can no longer be 3 red (to indicate "not 3"). Row 3 and column 3 each have only one cell that can still be 3, so we color them green. This prevents a few more cells from being 3, so we color them red.

Look in box 8 (the center box in the bottom row of boxes). It has no cells that can be 3--they are all blocked by one of the green cells. This is impossible, so setting cell 2,2 to 3 must be a mistake, and we can eliminate 3 as a possibility from that cell.

This sure beats making the move, eventually getting stuck, and then having to erase all the incorrect moves you made (if you could remember them all, that is)!

Practice mode

Learning a new strategy is easier if you are able to practice it. For this reason, SudoKoach has a practice mode. You choose 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 useful when choosing which strategy to learn next: start with the more common strategies, and work on the less common strategies later.

Making the puzzle larger and smaller

To change the size of the puzzle, just resize the window. The numbers automatically shrink or grow 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 just 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?

"I just recently purchased your program and love it! Many thanks for an excellent program." Dr. Allan P.

It's a lot more fun to play SudoKoach than it is to read about it! Why not download the 30-day free trial and try it out?

Order SudoKoach Now! Download the free trial now!

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