I stumbled across this little gem while looking for other examples of Turn-Based Strategy games.  I found a few examples of open source TBS games, and this by far and away the best: Battle for Wesnoth.  It has intriguing game play and excellent game mechanics; the graphics and sound are a bit simple but it takes up only 140 MB and runs great in Windows mode.  If you're a fan of the genre, check it out!

And you can't complain about the price!!

Oh I love this game.
Its fun and challenging without being Long and complex.
Plus its polished enough that it doesn't have that "Open Source incompleteness" feeling that a lot of OS games have.

And since modding it looks to be pretty easy, I have toyed with the idea of making some freedom force units just to see how it would work. If only I had more time than ideas...

It's actually been mentioned twice recently on the freeware threads.

But yeah, it's an excellent game and one that would be worth paying for, only you don't have to.