Warzone 2100 - Join "The Project" to restore humanity's synaptic-link technology after nuclear war...
FreeCiv - Freeciv is an open-source, turn-based strategy game based on Civilization II.
OpenRA - What if Albert Einstein changed history? What if the Andromeda Strain were a miracle mineral?
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.
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.
Sid Meier’s Civilization VI - Sid Meier’s Civilization VI is a Turn-based Strategy, War, Tactical, Single and Multiplayer video game created by Firaxis and published by 2K.