FreeCiv is an Open Source clone of Civilization® by Microprose® Win Mac X Linux
Freeciv is a free turn-based multiplayer strategy game, in which each player becomes the leader of a civilization, fighting to obtain the ultimate goal:
To become the greatest civilization.
Players of the Civilization® series by Microprose® should feel at home, since one aim of Freeciv is to have optional modes (called rulesets) with compatible rules.
Freeciv is maintained by an international team of coders and enthusiasts, and is easily one of the most fun and addictive network games out there!
That also means it has very extensive multilanguage support, something rare in games.
http://freeciv.wikia.com/wiki/Download
The goal
The goal of Freeciv is to build cities, which in turn can build armies to attack the other players. With default settings, you start with 2 settlers, 2 workers, and 1 explorer. Using the numeric keypad, move the settlers to a good location (see below) and build a city by pressing b (for build). You can move diagonally, by the way. Freeciv is turn based; every unit can move once per turn. The turn ends when everyone clicks Turn Done or when a timeout is over.
In a city, you can also build improvements which can help the city grow and prosper. Some improvements let a city get bigger. You should also build wonders, as they can do very important things; for instance the Apollo Program lets you see the entire map.
Cities also produce units, which can be used for various purposes, from fighting wars to enhancing infrastructure. Different strategies depend on different focuses between things external and internal to a city.
The eventual goal of the game is to win either by using military units to conquer all opposing civilizations, or by using massive scientific knowledge and production to build a spaceship to send to Alpha Centauri before your rivals can do so.
https://sourceforge.net/projects/freeciv/
https://sourceforge.net/projects/freeciv/files/latest/download
http://freeciv.wikia.com/wiki/DownloadOther Versions for Various OSes:
http://freeciv.wikia.com/wiki/More_distributions