Borders is a game concept that represents a nation's territory. They are optional in most rulesets; when they are on, you can see the lines in player-specific color that surround his or her territory (they can represent actual state on explored but currently invisible tiles, or not). There is a server setting that makes everything within the border visible. Your cities can't work tiles in another player's borders even if they are within their city radius (but can work unclaimed tiles). For some government and some game settings, citizens are unhappy if the player's military units leave his (or his ally's) borders. Finally, bordered area is calculated in the final score.

Rules of claiming for a tile[]

Generally, borders are recalculated at turn end, but their changes are handled immediately at events like building a claiming base or conquering a city. In some settings, you can't claim what you don't see, while in some another, you claim and then see what you have claimed.

Borders are not static in Freeciv but can move even if they separate friendly nations. You can't make a specific border treaty, but the claimed tiles are identified automatically around border sources that are mainly cities, and also some (owned) bases.

Several closest tiles around a city always belong to its owner unless an older city have the same claim on them. For other tiles, squared border radius for a single city staying in midland equals to a constant plus city population (capped with maximal city squared radius that equals to 26) multiplied on another constant, and bases have "border_radius_sq" property that identifies their radius. If several border sources have interferring radii, that one wins the claim that has bigger border strength on the tile (the tiles of the sources themselves are not questioned). The strength is basically 1 for bases and (2+population) for cities, and then the value is squared and divided without remnant on squared distance to the tile (i. e., bases have strength 1 on closest tiles and 0 elsewhere). Since strength of a border source on a tile must be strictly bigger than strength of current claiming source to reclaim, usually older sources have the priority.

An oceanic tile can be claimed if and only if one of the following conditions stands:

  • it is an inland lake not larger than MAXIMUM_CLAIMED_OCEAN_SIZE=20 (the source must be on the surrounding continent)
  • it is adjacent to only one continent (the source must be on it) and not more than two ocean tiles
  • It is one tile away from a border source
  • Player knows tech with Claim_Ocean flag
  • Source itself is Oceanic tile and player knows tech with Claim_Ocean_Limited flag

Ruleset settings[]

Parameter min max default Explanation
game.ruleset: [borders]
radius_sq_city 0 401 17 Base border radius from a city
size_effect 0 100 1 How much the squared radius grows with each new citizen (from 1st to 26th).
radius_sq_city_permanent -26 401 0 Difference between the squared radius of the "proper" tiles of the city (for which claiming strength is not important) and city squared workable radius. Minimal value means that there is no such tiles, maximal means that all that has got into borders will not be disputed by claiming strength.
game.ruleset: [playercolors]
colorlist table{"r", "g", "b"} Lists default colours to assign to players.
nations.ruleset: [nation*]
color.(r,g,b) 0 255 - Preferred colour (if plrcolormode = "NATION_ORDER")
terrain.ruleset: [base_*]
border_sq -1 0 or more means that the base is claiming this squared radius.
effects.ruleset: [effect_*] (type = "City_Radius_Sq")
value Increases city workable squared radius (that serves as a base of "proper" tiles squared radius). It's possible that border radius is smaller than working one.
techs.ruleset: [*]
flags "Claim_Ocean" Player claims ocean tiles even if they are not adjacent to border source
"Claim_Ocean_Limited" Oceanic border sources claim ocean tiles even if they are not adjacent to border source

Game settings[]

Setting Value Explanation
borders DISABLED No borders in the game.
ENABLED Borders exist, don't give vision, don't expand into unknown territory.
SEE_INSIDE Everything within borders is visible but unknown tiles can't be claimed.
EXPAND Everything within borders is visible, borders expand into the unknown.
foggedborders TRUE/FALSE If set to FALSE, players will know who now owns any tile they know even if it is not seen in the moment.
happyborders DISABLED Military units produce agressive deployment unhappines when not in a city or on a base with "NoAggressive" flag within square 7x7 (or equivalent hexagon) centered at player's or allied city.
NATIONAL Units also are not considered deployed agressive anywhere within their owner's borders.
ALLIED Units also are not considered deployed agressive anywhere within their owner's allies' borders.
plrcolormode PLR_ORDER Assign colours to each player in order by the colorlist (cycling if needed). The default mode.
PLR_RANDOM Take random colours for each player from the list.
PLR_SET Set colours manually (/playercolor PlrName aabbcc).
TEAM_ORDER Colours will be set to whole team in order (cycling if needed).
NATION_ORDER Colours will be set per nation, in order.