Freeciv

FreeCiv is an enjoyable strategy game very similar to Civilizations II in which you should lead your nation to a powerful civilization by founding cities, working the land, researching science, trading or fighting with other nations.

Before being able to play the game you will have to connect to a server with the client, either locally or somewhere on the net. The game features great graphics and offers a series of multiplayer capabilities over the net. One thing I didn't like about the game, is that it is a turn based game, so the player who has finished his turn waits for other players to finish their turn to continue the game. However, it features a very extensive multilanguage support, that is not commonly found in free multiplayer games. What I did like about the game is that it is fully customizable and provides multiple options to select exactly the thing you want. You can even select your country flag; different scenarios which vary in difficulty and extension; leaders of your country, either females or males; and many other things. The game can be run on Linux, Microsoft Windows, Mac OS X and Solaris, and is one of the most enjoyable and addictive network games out there. You will never regret downloading it.