Cooperstock Software
Sudoku Games

Introduction

A few years ago, I wrote a Windows program (using PowerBuilder) for playing or solving Sudoku puzzles, just for fun, because I love programming and I love doing Sudokus. Unfortunately, when this year (2026) I wanted to make some improvements to it, I found that in a switch between computers I had somehow lost the source code. So I re-wrote it, with those desired improvements.

To be clear, this is not like a lot of Sudoku apps available for phones etc., that have hundreds of Sudoku puzzles in them that you can play. I do include about a dozen sample puzzles, but that's not really the point. My reasons for programming this were first, to see if I could figure out clear algorithms (programmable rules) that matched the way I manually play Sudoku every morning from my newspaper, and second, to help solve any really hard ones I got stuck on (or had messed up!). So if you want to use the applications after working through my samples, you will have to manually enter puzzles that you got from elsewhere!

Subsequent to programming this in PowerBuilder, in order to have some more programming fun, I decided to learn a new-to-me programming language (Pascal, in the development environment Delphi), and manually "port" (translate) my PowerBuilder Sudoku application into Delphi. (I.e. I did that with no translation help from AI, except to help me figure out anything about Pascal and Delphi that I was unsure about.)

After that, I thought of doing the same with C# (Microsoft's main programming language) but wasn't sure I wanted to spend the time entirely re-learning C# (which I learned, a bit, about 20 years ago), and then re-writing it again in that language. Instead, I tried a few AI services, asking them to translate my Delphi code to become a C# program. The results from Claude and ChatGPT were astoundingly good - the results worked (or had just a few compile errors, and/or visual issues, that were easy to fix). Subsequent to that, I did some largely manual re-writing of the C# code to be more "idiomatic" for that language.  (Specifically, I changed "1-based" arrays in the AI translated C# code, which just ignored array element 0, to be truly 0-based.)

Finally I asked Claude AI to translate the C# version to be a web application, which it did basically perfectly on the first try. Amazing!

Having done all of that, I decided to make both usable applications and the source code (saved in GitHub) to all four of these Sudoku programs available on this website (which I created largely for this purpose).

How to use the Programs

Each version of the program below has a Help button when you run it, that brings up a comprehensive PDF help file. If you want to read about the programs before you download them, here's a link to the PowerBuilder version Help file.  Most versions are virtually identical, however the PowerBuilder version has an additional "Step" button that the others didn't bother implementing, and some additional options on the Options window.

PowerBuilder Sudoku:

• Installer for Windows:  https://github.com/cooperstock-software/sudoku-solver/releases/download/v2.1/SudokuSetupPB.exe
  Note: When you try to run the downloaded file, your computer's virus checker will also check it, and will likely complain because it's downloading from a little-used website. If it's Microsoft Defender, you will have to click the "More info" link, then click "Run anyways" to run the install.

• Source Code: https://github.com/cooperstock-software/sudoku-solver

Delphi Sudoku

• Installer for Windows: https://github.com/cooperstock-software/delphi-sudoku/releases/download/v2.1/SudokuSetupDelphi.exe
  Note: When you try to run the downloaded file, your computer's virus checker will also check it, and will likely complain because it's downloading from a little-used website. If it's Microsoft Defender, you will have to click the "More info" link, then click "Run anyways" to run the install.

• Source Code: https://github.com/cooperstock-software/delphi-sudoku

C# Sudoku

• Installer for Windows: https://github.com/cooperstock-software/CSharp-sudoku/releases/download/v2.1/SudokuSetupCSharp.exe
  Note: When you try to run the downloaded file, your computer's virus checker will also check it, and will likely complain because it's downloading from a little-used website. If it's Microsoft Defender, you will have to click the "More info" link, then click "Run anyways" to run the install.

• Source Code: https://github.com/cooperstock-software/CSharp-sudoku

Web Page Sudoku

• Play Here in a web browser on a computer, not on a phone or tablet. See the last bullet point in this section for why not!
  If you want to use the Load button to load sample games, download and extract sampleGames.zip to a folder where you can find the extracted files, and when you click the Load button, navigate to there to load the files.

• Source Code: https://github.com/cooperstock-software/web-sudoku

• Note: Amazingly, this version is the fastest at solving hard Sudoku puzzles like the sample hardest-inkala.sud, which at least at one point was supposed to be the hardest Sudoku puzzle ever created! That means that JavaScript (the programming language used for code in web pages) is incredibly fast in modern web browsers.

• Why I don't recommend trying to play this on a phone or tablet: I don't think there would be any way to bring up a keyboard to enter numbers for any new puzzles you wanted to play. Also, the small 1-9 number controls for manual play would be so small that trying to touch just one with a finger (given that you don't have a mouse with fine control on such devices) would likely not work.