FreeCiv - Freeciv is an open-source, turn-based strategy game based on Civilization II.
ANNO - ANNO is a city-building and economic simulation video game series, with real-time strategy elements.
C-evo - C-evo is a freeware empire building game for Windows
Tropico - Tropico is an Addictive, Strategy, Construction and Management, City Building, Sandbox and Single-player Simulation developed by PopTop Software.
0 A.D. - 0 A. D. is a free, open-source, historical Real Time Strategy (RTS) game currently under development by Wildfire Games, a global group of volunteer game developers. Download 0 A. D.
Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.