Hedgewars - Hedgewars is a Free to play, Single-player and Turn-based Strategy video game developed by Hedgewars Development Team.
TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Counter-Strike 2D - Top-Down Multiplayer Shooter
ThumbZilla - Awesome thumb stomping and kicking action game.
Ironfell - Ironfell is a time travel themed massive multi-player online real time strategy game.
Warlight - Warzone is a customizable Risk-like strategy game where you compete with your friends to conquer the world.