Freeciv 2.1.6

Freeciv is a Free and Open Source empire-building strategy game inspired by the history of human civilization. The game commences in prehistory and your mission is to lead your tribe from the stone age to the space age...
Freeciv is much more than a game: In Freeciv the game players can decide what the rules will be! This means that unlike nearly every other computer game, Freeciv *can* be a different game each time you play. This opportunity comes with some cost. Especially at first, a player trying to tackle all the subtleties and nuances of this complex gaming experience can get a little lost. It can be overwhelming, even.
No need to panic: The opportunity to make the game complex also means you can make it quite simple to play. You can even get up and playing one of the default scenarios within a matter of minutes