FreeOrion

FreeOrion is a turn-based strategy game of galactic conquest inspired by the Master of Orion games. As is typical for 4X games, players have to explore their surroundings, colonize new planets, manage their economies, research spectacular technologies, build up military might and conquer their neighbors, and ultimately, the entire galaxy. Features specific to FreeOrion are the diverse fantastical species and peculiar history of the game galaxy, the design of new ships with a multitude of hulls and ship parts available after research, and the possibility of technological victory after researching transcendence.

There is an impressive in-game encyclopaedia and most things can be looked up by clicking hyperlinks in messages or through right-click menus. The encyclopaedia includes both generic FreeOrion help and backstory as well as current game info such as for example what the target population of a particular planet would be if you were to colonize it with each of the species in your empire.

The game's source code is licensed under the GPL v2 and its media under the Creative Commons Attribution-ShareAlike 3.0 license.

The galaxy
The galaxy is a 2D region divided into a number of systems as decided before game start. Each of these may contain a star, or it may be empty. As long as a system contains a star there may be one or more planets. Nebulae on the galactic map obscure vision and over time collapse to form new stars in empty systems. If the game is started in a younger galaxy this may be a relatively frequent occurrence with many nebulae and few stellar remnants. Artificial black holes may be required to build some endgame tech if that is the case.

There are nine planet types arranged in a ring describing how similar they are. E.g. desert planets are adjacent to tundra and terran planets, terran to both desert and ocean, with sequence Tundra ↔ Desert ↔ Terran ↔ Ocean ↔ ... ↔ Tundra. With early game technology each species lives well on the same type as its homeworld ("Good"), acceptably on most adjacent planets ("Adequate") and depending on other factors may survive on the next over ("Poor"), while it will rapidly die out on the four remaining types ("Hostile"). Terraforming technology can be used to shift a planet&mdash;one step at a time&mdash;closer to the ideal for its current inhabitants.

Planets come in sizes ranging from tiny to huge, with uninhabitable (except by inferior "exobot" colony) asteroids belts and gas giants as well. Late-game technology can convert them into habitable worlds. Alternatively gas giants may be used for power generation and asteroid belts may support construction facilities for hollowed-out asteroid ships and inexpensive armor plating. Simply placing outposts on them will allow an empire to extend its supply lines through otherwise empty territory. Larger planets more easily support larger populations but smaller planets get a bonus to supply and larger planets a penalty due to the ease of launching to space. This can be overcome with space elevators.

Planets may have natural status effects. Especially the most valuable are sometimes inhabited by ancient robotic guardians which indiscriminately shoot at nearby ships.

Nearby systems are connected by fixed star lanes for ships to travel through. Later in the game technology becomes available to manipulate star lanes&mdash;and even to move entire planets through them.

Monsters roam the galaxy.

Population
In FreeOrion, each empire begins with a single species but can incorporate other species into the population by conquest. A planet is inhabited by a single species and each species prefers to live on a particular one of the 9 available planets (except exobots and one species who live on gas giants). The larger a planet and the more suited to the species preference, the larger the population that can be supported. (The population will naturally grow or shrink towards that limit.) Other resources such as research points and industry which a planet can support, are dependent on the size of the population. When the population of a planet focuses on a specific task&mdash;such as research or industry&mdash;they produce more of that resource but it can take time for a focus change to take full effect. Species have additional traits making them more or less useful in particular situations. Some species are more tolerant of environments they don't like. Some species are better at defending their planets from invasion or get more out of their ships' weapons. Some are better at research. New planets can be colonized either directly by colony ships, or indirectly by first building an outpost and then constructing a colony at the outpost.

Industry and stockpile
The industrial base of a planet provides Production Points, which are spent on constructing ships, buildings, and colonies. Ships also need to be maintained, which is expensive compared to building them. Any excess production points are stockpiled. There is a maximum rate at which any item can be built. When a planet has a large number of PPs available, it cannot build one object faster but can build many simultaneously. It is however possible to build slower than the maximum if too few PPs are available.

Research
As with industry, planets can produce research points and any one technology can be researched at a given maximum rate. The tech tree determines which options are currently available based on what has already been researched.

Supply
Planets and outposts can also produce supply. This resource is needed to link planets together for the purpose of internal trade & industry as well as for supplying fleets. Ships outside supply range from the nearest friendly planet will consume fuel when traveling through star lanes. When two or more planets are supply-linked, they share a common industrial pool and those planets building things will draw the excess production points of their neighbors. If planets are not in a supply pool, excess from one pool will have to be dumped into the imperial stockpile which other pools can drain at a limited rate.

Detection
Planets and ships have detection. They are able to see further as the detection limit is upgraded by technology or special buildings and ship parts. Stealth effects make ships and buildings harder to see at a distance.

Version history
See FreeOrion release history.