Widelands is a free and open-source real-time-strategy (RTS) game that is heavily based on The Settlers I & II game series by BlueByte. Widelands has three Tribes to choose from (Barbarians, Imperials and Atlanteans), your goal is to build, maintain and protect a flourishing settlement in four unique worlds (Greenland, Winterland, Blackland and Desert).
Mac OS X 10.4 or newer
Intel powered Mac
Free download at wl.widelands.org