Does the world need yet another printable Sudoku puzzle software? Of course it does. I wanted to make one using my creaky spreadsheet programming skills. Along the way, I made a startling discovery…

Get Printable Spreadsheet Sudoku Now!

If you just want the spreadsheet, here’s what you have to do:

• Go to Morphoboard.com
• Register
• Check your email to confirm your subscription
• Get instant access, both online and via download

The Nitty Griddy

Okay, they’re gone. For the geeks remaining in the room, let me wow you with this revelation:

Sudoku puzzles are nothing more than collections of cryptograms!
This does not mean you can solve a Sudoku puzzle like a Cold War spy. Maybe.
But if you want to quickly create an absurdly large number of puzzles, you no longer have to create a tentative puzzle and exhaustively check it for accuracy. Just grab your code key and translate one Sudoku puzzle into another! I’ll demonstrate the technique with pictures.

Consider the first grid to be the solution to a particular Sudoku puzzle. Consider a substitution key where 1 becomes 4, 2 becomes 9, 3 stays 3, 4 becomes 5, 5 becomes 8, 6 stays 6, 7 becomes 1, 8 becomes 2 and 9 becomes 7. After translating the first grid, we arrive at the second grid!
Now that you know the “secret”, you can use your favorite program to generate new Sudoku Puzzles!

Here are some tricks I used for Printable Spreadsheet Sudoku:

1. I randomly select one of 99 different solutions
2. For the substitution key I use one of the rows in the solution!!
3. I randomly shift and rotate the grid, ensuring that the puzzle remains intact
4. Blank squares are randomly displayed – more blanks mean a tougher challenge

I limited the total number of possible combinations because I figured 48,000 puzzles are enough. By the time you finish them, you won’t even remember the first batch and you can play all over again!

Who’s Out There?

I wanted to see if anyone else had created Sudoku Puzzles based on substituting values. I discovered an interesting site:

This site has a Sudoku variation called Twin Corresponding Sudoku. Henry Kwok is the author.
This variation requires you to use cryptography in order to help solve both puzzles simultaneously. As an aside, I believe I have found the original creator of this variation. He has a lengthy post on a forum, discussing his invention:

With my friends and even some strangers, I have discussed the problem of my sudoku variants popping up here and there like mushrooms on some websites, in books and some international championships. Among them, the opinion of one person, who has a deep interest in Zen, is particularly interesting.

I almost fell off from my chair when he said that such happening shows that my sudoku variants are a great success and it should be viewed as a positive development. He said that my task is to make it “more positive” by thanking whoever is interested in my sudoku concepts and encouraging him to use more of my ideas, whether on websites or in books! He said that I cannot force others to advertise for me, but others cannot stop me from advertising myself . He said I can never stop others from using my ideas, and similarly others can never stop me from trying to get the maximum benefit out of the whole situation.

Now I am putting the advice of that “Zen master” into practice to see how successful it works.

First I have to thank http://www.sudokumasters.in for using my idea of “Twin Corresponding Sudoku” in its so-called “Substitution Twin Sudoku”.

… An article in http://www.notelay.com/articles/did_you_know/what_is_sudoku/ has this interesting comment about sudoku: “Because Sudoku is logic-based, other puzzles could be created that use the same concept and replace the numbers with other objects, such as colours, letters or shapes.”

I have used graphics, Chinese words and the alphabet for my Twin Corresponding Sudoku. Please refer to the following websites:

http://nrich.maths.org/public/viewer.php?obj_id=5518

http://www.ageofpuzzles.com/Collections/TwinSudokus/TwinSudokus.htm

http://www.chinasudoku.com/

I have to thank http://wsc2008.com for designing its so-called “Alphabet Substitution Twins”. Whatever name the “new” puzzle is called, it is still identical to my “Twin Corresponding Sudoku”.

Finally, I hope more people will use my sudoku ideas freely on their websites and in their books, but at the same time as the Chinese saying goes, “remember the source whenever you drink water”, so please don’t keep me totally out of your limelight.

- aman, on Phorum 5 (and elsewhere, evidently)

There ya go, Henry!