For geeks like myself, there is only one thing better than free software – open-source software. The reason for this is fairly obvious. In addition to being free, the source code is available for you to view and modify or reuse. The open-source movement has led to some of the most popular software in use today. The Firefox Web browser is a result of the open-source Mozilla browser, and Mac OSX is based on the open-source family of UNIX Operating Systems.

Over the next couple of weeks we're going to look at some of the open-source software available for Windows Mobile. If you have an open-source app you'd like us to cover, let us know in the comments.

Pocket Sudoku, developed by Emil Andersson, is an application that I’ve used for a number of years. Currently in Version 1.0, it allows you to play several Sudoku style games within one interface.

Read on for the full review.

## The basics

If you're a longtime Sudoku player, skip ahead. For the uninitiated, Sudoku is a number-based logic puzzle that's as simple as it is infuriating. Here's the Wikipedia definition:

Sudoku is a logic-based number-placement puzzle. The objective is to fill a 9×9 grid so that each column, each row, and each of the nine 3×3 boxes (also called blocks or regions) contains the digits from 1 to 9 only one time each. The puzzle setter provides a partially completed grid.

## Quality

One of the biggest issues with open-source software is that often the application can become stuck in a perpetual “beta” status. This does not necessarily cause any major problems (think gmail) but is worth mentioning. I haven’t noticed any issues Pocket Sudoku. The developer took into account several different styles of the Sudoku game as well as different techniques that players will typically use. One benefit is that the software utilizes Microsoft’s ClearType functionality to give you crisply rendered, easy-to-read fonts.

## Functionality

Pocket Sudoku allows play from beginners to experts. Various grid sizes and difficulty levels will allow for any level of play. Pencil marks can be used manually or can be automatically filled in for you. Switching between numbers can be accomplished by tapping on a previously entered number or by cycling through all of the numbers by tapping on the current number at the bottom right of the screen. Adding a pencil mark or removing a previously entered number are both accomplished by tapping and holding the target square.

## Conclusion

Pocket Sudoku is what open-source software is all about. That a developer in this day and age would share an application of this quality at no cost is amazing in and of itself. Having the source code being available for other developers to dissect and learn from is even better.

If you like Sudoku (or would like to learn), this application is a must have. Keep an eye out for updates, and consider making a donation to the developer in order to keep the development going.

## Ratings (out of 5)

• Quality: 5
• Functionality: 5

## Pros

• Open source, and it's free
• Allows for many different skill levels
• Uses ClearType so you don't destroy your eyes

## Cons

• Not supported in the same way as most commercial software