Battle for Wesnoth

The Battle for Wesnoth is a turn-based tactical strategy game with a high fantasy theme. Build up a great army, gradually turning raw recruits into hardened veterans. In later games, recall your toughest warriors and form a deadly host that none can stand against! Choose units from a large pool of specialists, and hand-pick a force with the right strengths to fight well on different terrains against all manner of opposition. Source available on GitHub.