FreeCiv is a free, open source, turn-based strategy game that is influenced by the long running civilization series of games. In FreeCiv, you take on the role leading your chosen civilization out of the Stone Age and into the Space Age. You must explore, build out, and research new skills and abilities, all while trying to defeat the rival civilizations that are doing the same thing. FreeCiv has been in development for over 18 years and boasts a large community with years of information and resources.
FreeCiv features various difficulties of AI, single player and multiplayer capabilities, randomly generated maps, rule fine-tuning, and tons of other things to make each game a totally different experience.