About Sudoku

Even if you don’t know how to play Sudoku, you’ve probably heard of the game or seen one of the puzzles in a magazine or newspaper. Astraware Sudoku is a PalmOS version of this addictive game consisting of a 9×9 grid containing numbers or empty cells. The grid is broken up into smaller 3×3 grids that look like figure 1.

The goal of the game is to fill in the blank spots with the correct numbers, making sure that the numbers 1 through 9 only appear once in each column, each row, and each 3×3 grid. Sounds easy, right? Well, yes and no.

Learning to Play

For the novice, Astraware provides three options for learning how to play Sudoku. There is a built-in tutorial as well as a PDF user guide that teaches you the basics of how to play and the unique features of Astraware Sudoku. But if you really want to become a Sudoku master, you should check out Astraware’s Sudoku web site which has an in-depth tutorial on the different techniques you can use to solve Sudoku puzzles.

I’ll just cover the basics here. As mentioned earlier, the goal is to fill in the blank cells with the correct numbers. How do you do this? Essentially, you use the process of elimination so that guessing is only used as a last resort.

Looking at Figure 1, let’s start with the first cell in the upper left. Based on the rules of the game, we initially know this cell will contain a number from 1 to 9. But if we look at the numbers in the same row, we can eliminate the numbers 8, 6, 3, 1 and 9. This leaves us with the 2, 4, 5, and 7 as possible choices. However, if we look at the numbers in the same column, we can also eliminate the numbers 2, 5, and 7. This means that the only number left is 4, which is the correct number for the upper-left cell. Repeat this process for the remaining cells and you’ve completed the puzzle.

Sounds simple, right? Well, that was a very simple example, and as you play the game (especially the more challenging levels) you will find that this process of elimination often leaves you with several possible choices for a cell and this is where the game becomes more challenging. You can use the brute force method of identifying all possible candidates for every open cell and this approach will often be good enough for the easier levels because you’ll eventually find a cell with only one possible candidate. And once you fill in that cell you can eliminate that number as a candidate from the other cells in the same row, column and 3×3 grid. This often results one or more of those cells having only one possible value, allowing you to repeat the process until all of the cells are filled and the puzzle has been completed.

However, the higher difficulty levels require more advanced techniques with names like “X-Wings”, “Swordfish” and “Forcing Chains” that make Sudoku an easy game to learn but difficult to master.

What Makes Astraware Sudoku Special?

Better Than Paper - Compared to playing Sudoku on paper, Astraware adds the convenience of letting you carry thousands of puzzles with you wherever you go. It also keeps track of how long you take to solve each puzzle, letting you see how your Sudoku skills are improving.

Astraware Sudoku also lets you do the same things you would do when playing on paper. This includes things like making “pencil marks” to indicate your guesses for each cell using small numbers as show in Figure 2.

And if you are ever reduced to guessing, the Notepad mode shown in Figure 3 comes in useful by allowing you to write in a guess and then see what sort of impact it will have on the other cells, without officially entering into the cell. And you can quickly toggle back and forth between this view and the normal view with a single keystroke.

Assistance and Hints

To help you with learning the game, there are “assistance” settings for things like Auto Pencil marks, Forbid Mistakes and Flag Mistakes that make the game easy and fun to learn. But as you develop your Sudoku skills you will probably want to turn these features off in order to duplicate the challenge of solving the puzzle on paper without knowing if you have correctly solve the puzzle until you check it against the solution when you are done.

Pick Your Difficulty Level

Astraware Sudoku has puzzles grouped into six different levels of difficulty, from Beginner to Diabolical, so you can start out easy and work your way up to the more challenging puzzles. This helps beginners avoid getting frustrated with a puzzle they can’t solve or more advanced players getting puzzles that they think are too easy. Whatever your skill level, you can always find the puzzle difficulty you want.

Downloadable Puzzle Packs - The Astraware Sudoku web site has a download section where you can download literally thousands of additional puzzles. You can install them via HotSync or if you are on the road you can download directly into your Treo using your Treo’s web browser. There are currently 10 puzzle packs per difficultly level (as well as mixed-level packs) and since each pack contains 100 different puzzles, that’s over 1,000 new puzzles for each level. And if you somehow finish all of these puzzles you can get even more with Sudoku of the Day.

Sudoku of the Day – Just like playing the daily Sudoku puzzle in your newspaper, Sudoku of the Day allows you to download a new set of puzzles each day from Astraware without leaving the game. Just select Puzzle of the Day from the main menu, pick the difficulty level, and you’ll be playing the downloaded puzzle within seconds.

And when you finish a puzzle, you have the option of positing your time on the Astraware web site and seeing how you compare to other Sudoku of the Day players.

Add or Create Your Own Puzzle – Given the thousands of puzzles you can download, you probably won’t run out of puzzles to play. But if you do, you can have Astraware Sudoku create new puzzles for you or you can enter puzzles from a magazine or newspaper that you want to solve.

Conclusion

Astraware Sudoku is a great game for beginners and experts alike. And with the thousands of puzzles you can download and the Sudoku of the Day feature, you will never run out of Sudoku puzzles to play.

Pros:

• Easy to learn, difficult to master

• Thousands of puzzles wherever you go
• Different difficulty levels let you pick the game that’s right for you.
• “Puzzle of the Day” not only ensures you have new puzzles each day, but also lets you compare your performance to others.
• Astraware Sudoku web site has a wealth of information on playing Sudoku

Cons:

• Puzzles aren’t uniquely identified, so you can’t easily compare your performance on a specific puzzle against another user (unless playing a Sudoku of the Day puzzle)

• Would like more information about the puzzles that have been installed, including information about how many puzzles have been solved and how many remain.

Related Links

Buy Astraware Sudoku

Astraware Sudoku Information and Strategy Guide

Sudoku of the Day

Puzzle Pack Downloads

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