TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Tropico - Tropico is an Addictive, Strategy, Construction and Management, City Building, Sandbox and Single-player Simulation developed by PopTop Software.
ThumbZilla - Awesome thumb stomping and kicking action game.
Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.
Warlight - Warzone is a customizable Risk-like strategy game where you compete with your friends to conquer the world.
Age of Empires - Age of Empires is the critically acclaimed, award winning Real Time Strategy (RTS) game with a legacy spanning over 20 years and nearly a dozen titles in the franchise.