FreeOrion Open Source Space Empire and Galactic Conquest Game
FreeOrion is a free open source turn based space empire and galactic conquest game for Linux, Windows and MacOS. It is based on classic 4X model and inspired by the Master of Orion games. It is released under the terms of the GNU GPL 2.0 and CC-BY-SA-3.0 license. It comes in single player and multi player modes and you need at least OpenGL 2.1 support to play this game.