Hidden Empires has got a pretty unique theme:
Hidden Empires II is a game for 2 to 6 players where each player assumes the role of an ant colony. You will guide your colony as it attempts to grow and thrive in a hostile environment while competing for resources with neighboring colonies. Your colony will employ unique survival strategies based on those of real world ant species. To win the game, you must give your species the best chance of survival by producing more reproductive ants than your opponents.