Freeciv is a single- and multiplayer turn-based strategy game for workstations and personal computers inspired by the proprietary Sid Meier's Civilization series. It is available for most desktop computer operating systems and available in an online browser version. Released under the GNU GPL-2.0-or-later, Freeciv is free and open-source software. The game's default settings are closest to Civilization II, in both gameplay and graphics, including the units and the isometric grid. However, with a lot of multiplayer games being played in longturn communities, rulesets and additional variants have evolved away from the original ruleset. Freeciv is playable online on various public and private servers.

Players take the role of tribal leaders in 4000 B.C. who must guide their peoples through the centuries. Over time, new technologies are discovered, which allow the construction of new city buildings and the deployment of new units. Players can wage war on one another or form diplomatic relationships.

The game ends when one civilization has eradicated all others or accomplished the goal of space colonization, or at a given deadline. If more than one civilization remains at the deadline, the player with the highest score wins. Points are awarded for the size of a civilization, its wealth, and cultural and scientific advances.

At the computer science department at Aarhus University, three students, avid players of XPilot and of Sid Meier's Civilization, which was a stand-alone PC game for MS-DOS, decided to find out whether the two could be fused into an X-based multiplayer Civilization-like strategy game. The students—Peter Unold, Claus Leth Gregersen and Allan Ove Kjeldbjerg—started development in November 1995; the first playable version was released in January 1996, with bugfixing and small enhancements until April. The rules of the game were close to Civilization, while the client/server architecture was basically that of XPilot.

For the developers, Freeciv 1.0 was a successful proof of concept, but a rather boring game, so they went back to XPilot. Other players and developers took over; they made the game available on many other operating systems, including Linux, Solaris, Ultrix, AmigaOS, and Microsoft Windows. Linux distributions started to include Freeciv.

The main development goal remained to make a Civilization-like game playable over the Internet, with participants on different continents, even when connected with 14400 bit/s modems. Freeciv achieved this by using an asynchronous client-server protocol: during each turn, human users play concurrently, and their actions are sent to the server for processing without awaiting the results. This kept the game playable with network latency up to a few hundreds of milliseconds.^{[citation needed]}

In 1998, computer players were added; they could soon beat newcomers to the game with ease, using only minor forms of cheating. Computer players are implemented directly in the server; they do not play concurrently with human players, but separately, in between turns.

The game grew in popularity. A public server was installed on which games could be played around the clock; it retained the games and published a post-game analysis webpage with per-player statistics and an animated map replay.