Freeciv is released as a binary for the Microsoft Windows operating system, but can be compiled for others. Released under the GNU General Public License version 2, Freeciv is free and open-source software.
Players take the role of a tribal leader in the year 4000 BCE, that has to guide their people through the centuries. Over time, new technologies are discovered, which allow the construction of new city buildings, and allow for the deployment of new units. Players can wage war on one another, or form strategic diplomatic relationships.
The game ends when one civilization has either eradicated all others, accomplished the goal of space colonization, or completed a set number of turns; if more than one civilization remains at the end of this turn deadline, the player with the highest score wins. Points are awarded for the size of a civilization, its wealth, and its cultural and scientific advances.
At DAIMI, the computer science department at Aarhus University, three students, whom were avid players of XPilot and of Sid Meier's Civilization, 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 available in a new version shipped in April of that year. The rules of the game were close to Civilization, while the client/server architecture was was inspired by 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. But, Freeciv was already playable and addictive enough for other students to play it, bugfix it, extend its features. It was useful enough to be picked up by popular Linux distributions, e.g. Debian.
Designed to be portable, it was later ported to many platforms, which helped its survival. Freeciv playing and development continues to the present day, although the spells with little development activity have grown longer and more frequent over time. The development history is strictly incremental: while there have been many serious improvements, the basic design and architecture has not changed since the early versions.
From 1998, the game grew in popularity: public servers often hosted several competitive games every day, archiving them and showing an animated GIF replay of each game on its website. In the years before the release of version 2.0 in 2005, the game remained largely unchanged. As many regular players became better players, diplomacy became essential, so team games slowly started to replace free-for-all games from around 2002. The release of version 2.0 in 2005 changed the game significantly; both new and tweaked rules favoured large cities with full trade routes, as well as wars with more advanced technologies, necessitating a distinct phase of "rapturing" which required relatively peaceful conditions. Games were thus almost always played in teams, and typically took longer to finish compared to pre-2.0 games.
Freeciv is very configurable, down to specific rules, so it can be played in Freeciv (default) mode, Sid Meier's Civilization, Sid Meier's Civilization II, or in a custom mode. One or several players act as game administrators and can configure the game rules. Typically modified rules are:
The number of players required before the game can be started
The speed of technological development
AI players allowed or not
Allowing AI-controlled barbarians to invade player settlements
How close cities can be built to one another
How continents and islands are generated and distributed over the map
Map topology (rectangular or hexagonal tiling, and whether it wraps horizontally and/or vertically)
In order to play a game of Freeciv, a user must start up the Freeciv client and connect it to a Freeciv server. Initially, the server is in pre-game phase; in this phase, clients can connect and game configuration parameters can be changed. At some point, the server may be ordered to start a game; in response, it creates game players (nations) and the game map, and assigns every player to either a Freeciv client or a computer player, as specified by the configuration. From that point on, the game will run until it ends or is terminated; the server can never get back into pre-game state.
The user can also start a game directly from the client: this automatically starts a local Freeciv server, connects to it and starts the game.
Freeciv's graphics system is configurable: originally, map display was always in overhead mode (like in Sid Meier's Civilization), which many players found rather crude; isometric mode (like in Sid Meier's Civilization II) was added later. In both modes, look can be further customized by switching to an alternative set of graphics (called a tileset). The sounds can be replaced as well.
Freeciv supports human-to-human multi-player gameplay and artificial intelligence (AI) computer players.
While the game is turn based, human players move simultaneously. The AI players move separately, partly at the start of a turn, partly at the end.
In releases before 2.0, AI players could not engage in diplomatic relationships with human players. Under the current release, AI players will engage in a very predictable, rules-based diplomacy.
Freeciv version 2.2.0 includes a map editor, termed Civworld. It can create new scenarios, as well as edit the map currently being played. Basic scripting is available with Freeciv, but is not available in Civworld.
Originally developed on IRIX, Freeciv has been reported to run on Mac OSGNU/Linux, Microsoft Windows, macOS and Solaris, along with a large number of other operating systems including Ultrix, QNX, OS/2, Cygwin, AmigaOS, Maemo 5, ZETA, SkyOS and various BSD distributions. Freeciv is also included with many popular Linux distributions. There is also a version of Freeciv playable online in a browser.