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.
openage - Free Age of Empires II clone
Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.
ANNO - ANNO is a city-building and economic simulation video game series, with real-time strategy elements.
OpenRA - What if Albert Einstein changed history? What if the Andromeda Strain were a miracle mineral?
Tropico - Tropico is an Addictive, Strategy, Construction and Management, City Building, Sandbox and Single-player Simulation developed by PopTop Software.