Unknown Horizons is a free and open-source 2D realtime-strategy (RTS) simulation game that is inspired by Sid Meir's Colonization and Sim City game series. Unknown Horizons' main focus and objective is on economy and city building. You begin by starting with small settlement and expanding it into to a strong and wealthy colony.
Mac OS X 10.4 or newer
Intel powered Mac
Free download at unknown-horizons.org