The Battle for Wesnoth is a Free, turn-based tactical strategy game with a high fantasy theme, featuring both single-player, and online/hotseat multiplayer combat. Fight a desperate battle to reclaim the throne of Wesnoth, or take hand in any number of other adventures. Easily modifiable. You can even download other users' add-ons from the main menu.
Great job on this game! Lots of fun. Very nice to look at and runs great even on my crummy old laptop.
I love TBS games and not many of them, even the ones you pay for, come close to this.