0 A.D. is a free, open-source, cross-platform real-time strategy game under development by Wildfire Games. It is a historical war and economy game focusing on the years between 500 B.C. and A.D. 500.[1][2] The game is cross-platform, playable on Windows, Mac OS X, and Linux.[3] The game aims to be entirely free and open-source, using the GPL 2+ license for the game engine and the CC-BY-SA for the game art. The game has been in development since 2000, with actual work starting in 2003. There is no official release date set for the finished version.