0 A.D. is a strategy game released in 2016 designed and developed by Wildfire Games. 0 A.D. can be described as a free, open source game and can be played on the following operating systems: Windows, Mac OSX, Linux. 0 A.D. is also a multiplayer game.
“0 A.D. (pronounced “zero-ey-dee”) is a free, open-source, historical Real Time Strategy (RTS) game currently under development by Wildfire Games, a global group of volunteer game developers. As the leader of an ancient civilization, you must gather the resources you need to raise a military force and dominate your enemies.” - Wildfire Games