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This document describes how to convert freeciv 2.4 compatible ruleset to development version (one that will become freeciv 2.5) compatible ones. Currently this goes up to compatibility with freeciv S2_5 revision 22815.

CapabilityEdit

Capability string of each ruleset file must be changed:

[datafile]
options="+Freeciv-ruleset-Devel-2013.Apr.23"

No more default fallbacks for individual ruleset filesEdit

In earlier versions it was possible to have ruleset similar enough to default one to actually use default ruleset files just by omitting that file from custom ruleset. That's no longer the case. This affects also ruleset specific script file script.lua, but fallback to default.lua that most rulesets should not implement themselves still works.

Use 'TRUE' and 'FALSE' instead of '0' and '1' for booleansEdit

Here the list of affected settings:

"cities.ruleset":

[parameters]
angry_citizens
changable_tax
vision_reveal_tiles

[citizen]
nationality

"effects.ruleset":

[effect_XXX]
reqs = { "negated", "survives" }

"game.ruleset":

[civstyle]
pillage_select

[illness]
illness_on

[global_unit_options]
slow_invasions

[combat_rules]
tired_attack

[calendars]
skip_year_0

"terrain.ruleset":

[parameters]
ocean_resources

[base_XXX]
buildable
pillageable

nation files:

[nation_XXX]
is_playable

Remove useless cruftEdit

The old road_superhighway_trade_bonus field is no longer read and should be removed. (It turned out it wasn't doing anything anyway; to control this, use effects.)
In nations rulesets, the is_available field is no longer read nad should be removed. It didn't do anything.

RoadsEdit

Road types sections must be added to terrain.ruleset. See classic terrain.ruleset for documentation and road types similar to old hardcoded ones.
"rail_xxx_bonus" fields are replaced by "xxx_bonus" fields in road definitions. To make exact conversion from old version, define each "xxx_bonus" zero for all other road types, but use old "rail_xxx_bonus" values for road type "Railroad"
"road_trade_incr" field for terrains has been replaced by "road_xxx_incr_pct" that tells how much of road type specific increase applies on this terrain. To make exact conversion from old version, define all other road type "xxx_incr" fields 0, but make "Road" "trade_incr" 1, and replace each terrain "road_trade_incr" with "road_trade_incr_pct" and value multiplied by 100.
There's only one road build time field for each terrain when previously we had both "road_time" and "rail_time". You may not be able to make exact conversion depending on your previous values. In the common case of earlier "rail_time" being same for all terrain types, you can make build time for road type "Railroad" road specific, not terrain specific by settings its "build_time" to value you used to have in terrain specific "rail_time"s.
"river_move_mode" is replaced with road type move mode. Set road type "River" "move_mode" to the equivalent value to what you used to have in "river_move_mode"
Set road type "River" defense bonus to value that used to be "river_defense_bonus"
Set road type "River" "trade_incr_const" to value that used to be "river_trade_incr"
Set road type "River" helptext to what used to be "river_help_text"
Set flags "River", "PreventsOtherRoads", and "Natural" for road type "River" to have it behave just like river special in earlier versions
Requirements on roads should be changed from checking Special Road, Railroad, or River to checking roads
```
"Special", "Road", "Local"
```
->
```
"Road", "Road", "Local"
```
Tech flag "Railroad" has been removed as obsolete. You should have such tech defined as requirement for road type "Railroad" in terrain.ruleset instead.
Unit class flag "RoadNative" has been removed as obsolete. Instead you should give flag "NativeTile" for road type "Road"
Unit class flag "RiverNative" has been removed as obsolete. Instead you should give flag "NativeTile" for road type "River"

BasesEdit

With some limitations it's possible to define terrain specific build time instead of base specific ones, or to disable base building completely on some terrain with new "base_time" field in terrain definitions. To make exact conversion from old version, give each terrain "base_time" field with non-zero value. Base specific build times are still used as they are available, and non-zero terrain specific value just makes sure that base building is not disabled on that terrain.

DisastersEdit

One may add random disaster sections to game.ruleset, but that's optional. If there's no disasters defined, none simply ever occurs. See default game.ruleset for documentation.

AI traitsEdit

Default traits section should be added to nations.ruleset
Optionally you can add also nation specific values for individual nations

Nations compatibilityEdit

In the supplied rulesets which use the standard nations, nations.ruleset is split into two files. The main nations.ruleset defines only global settings such as default traits, and includes a second shared file, default/nationlist.ruleset, which contains the list of individual nations to include. You can either include that same full list from your own nations.ruleset, or have a list of your own, or define nations directly in your ruleset.
The nation [compatibility] section has new fields allowed_govs, allowed_terrains, and allow_city_styles (replacing the boolean warn_city_styles), in which are listed the governments/terrains/city styles that individual nation definitions are allowed to reference. This is mainly for use in our nationlist.ruleset, so that if you include it in a ruleset which doesn't have a particular government (say Fundamentalism), any references to that government (e.g. in ruler titles) are silently ignored rather than causing an error. These fields are optional and not expected to be useful in rulesets which specify their own nations.

Unit conversionEdit

Converting unit to another is no longer instant operation. You should add "convert_time" field for each unit type that can convert to another.

Effect typesEdit

Prefered field to give effect type in is now type, though old name still works for backward compatibility reasons.

[effect_granary]
type	= "Growth_Food"
value	= 50
reqs	=
    { "type", "name", "range"
      "Building", "Granary", "City"
    }

Trade routesEdit

Number of trade routes city may have is controlled by new Max_Trade_Routes-effect. You have to add such an effect to make trade routes possible at all. To recreate old hardcoded behavior of all cities always having 4 trade route slots, you can add this:

[effect_trade_routes]
type    = "Max_Trade_Routes"
value   = 4

Traderoute settingsEdit

Some aspects of traderoutes are now defined in ruleset instead of being hardcoded. You have to add [trade] section to game.ruleset with traderoute specific settings. To recreate settings similar to old hardcoded rules, use these values:

[trade]
settings =
  { "type",       "pct", "cancelling"
    "National",   100,   "Cancel"
    "NationalIC", 200,   "Cancel"
    "IN",         200,   "Cancel"
    "INIC",       400,   "Cancel"
  }

Attack to non-native tilesEdit

To allow shore bombardment ability to sea units like the hardcoded one they used to have, give any sea moving unit class flag AttackNonNative.
Unit type flag No_Land_Attack renamed as Only_Native_Attack and it makes sense for those unit types only for which unit class has AttackNonNative

Attack from non-native tilesEdit

To allow ships to attack out of harbour cities like they used to with old hardcoded rule, give any sea moving unit class flag AttFromNonNative.

Governmental centersEdit

Corruption no longer depends on distance to capital city, but to nearest Governmental center. To make capital act as governmental center as in earlier versions, add "Gov_Center" effects with same requirements as you have "Capital_City" effects.

Nationality conversionEdit

Citizens of foreign nationality now slowly convert to city owner's nationality. Add convert_speed to [citizen] section of cities.ruleset. Set it to value 0 to disable conversion the way 2.4 worked.

Partisan appearanceEdit

Add partisans_pct to [citizen] section of cities.ruleset. Set it to value 0 to make partisan appearance to depend on who originally built the city, just like in the earlier versions. If you want to make partisan appearance now to depend on number of citizens of old owners nationality in city, set the required percentage instead.

PopulationEdit

It's now somewhat configurable how many people single point of city size represents. This is purely for values shown in reports. It has no gameplay effect. Add pop_report_zeroes entry to [parameters] section of cities.ruleset. Set it to value 4 to have population in tens of thousands as in earlier versions.

Terrain classEdit

Use of terrain flag Oceanic has been replaced by giving class field for all terrain types. Remove Oceanic flag from all terrains that have it, and instead add class = "Oceanic" for them and class = "Land" for all others.

Terrain conversionsEdit

All of Irrigation, mining, and transform actions are now possible only if relevant effects have positive value. In version 2.4 only basic Irrigation had such a control by Irrig_Possible effect. To make Irrigation and Mining, including terrain changes by them, always available like in earlier versions, define effects Mining_Possible, Irrig_TF_Possible, and Mining_TF_Possible without any requirements and with positive value. Transform action has never been always possible - it has required unit to have Transform flag. There no longer is such a hardcoded flag, but one can define equivalent flag as user unit type flag. Then one can give that unit flag as requirement for new Transform_Possible effect to have transform work like it did it earlier versions. The may_road, may_irrigate, may_mine, and may_transform boolean flags have been removed - use the *_Possible effects to control whether these actions are available.

Flooding LakesEdit

Other oceanic terrains now flood to FreshWater terrains when the two get adjacent. To ensure best behavior, you may want to change terrain conversions from land to oceanic terrain to have FreshWater target instead of oceanic one. Then the transformation will result in FreshWater when part of FreshWater lake, and without flooding the lake. If newly created FreshWater tile is part of Ocean, it will be immediately flooded in to part of Ocean instead.

Free tech selection methodEdit

You need to add setting free_tech_method to [research] section in game.ruleset. Value Goal gives behavior like old hardcoded functionality.

Use unit type flagsEdit

Old single array of user unit type flag names is replaced with table where also helptext to be shown for the units having the flag is present.

[control]
flags =
  { "name", "helptxt"
    "Airbase", _("Can build Airbases.") 
  }

Combat bonusesEdit

Old special flags Horse, Pikemen, AEGIS, AirUnit, Fighter, and Helicopter removed, and new combat bonuses framework introduced instead. Bonus is always defined for units benefitting from it in the combat. The unit bonus applies against, must have relevant flag, so you may need to define some user unit type flags equivalent of old hardcoded flags.

Horse vs PikemenEdit

To reproduce old Horse vs Pikemen flags behavior, define user unit type flag Horse. Remove old Pikemen flag from units, and define this kind of combat bonus for them instead:

bonuses       =
  { "flag", "type", "value"
    "Horse", "DefenseMultiplier", 1
  }

AEGIS vs AirUnitEdit

To reproduce old AEGIS vs AirUnit flags behavior, define user unit type flag AirUnit. Remove old AEGIS flag from units, and define this kind of combat bonus for them instead:

bonuses       =
  { "flag", "type", "value"
    "AirUnit", "DefenseMultiplier", 4
  }

Fighter vs HelicopterEdit

To reproduce old Fighter vs Helicopter flags behavior, define user unit type flag Helicopter. Remove old Fighter flag from units, and define these kind of combat bonuses for them instead:

bonuses       =
  { "flag", "type", "value"
    "Helicopter", "DefenseDivider", 1
    "Helicopter", "Firepower1", 1
  }

Max Rates of Cheating AIEdit

Cheating AI is no longer hardcoded to ignore Max_Rates limitations for tax/sci/lux settings. If you want Cheating AI still not to be subject to those limitations, you can add this kind of effect:

[effect_ai_cheat_no_max_rates]
type    = "Max_Rates"
value   = 100
reqs    =
    { "type", "name", "range"
      "AI", "Cheating", "Player"
    }

KillstackEdit

Killstack is now server option. Remove it from game.ruleset combat_ruleset section. If you want to force its value with your ruleset, you can add it as locked ruleset setting to settings listing in game.ruleset

[settings]
set =
  { "name", "value", "lock"
    "killstack", "enabled", TRUE
  }

KillcitizenEdit

Unit classes that kill citizens upon succesful attack against city are now defined in units.ruleset by giving them KillCitizen flag. To mimic old default value of killcitizen setting, give that flag to all land moving unit classes.

Minimum native start areaEdit

Add min_start_native_area value to parameters section of terrain ruleset. Set it to value 0 to accept any size of start area like earlier versions did. You will want set it to some other value only if your ruleset has terrain types non-native to startunits.

Civil warEdit

You can disable civil war entirely by including civil_war_enabled = FALSE. To get the previous default behaviour of allowing civil war, add civil_war_enabled = TRUE.

Game loss styleEdit

A new bitwise option gameloss_style controls what happens to a player's possessions if they lose the game by for instance losing their Leader unit. Set gameloss_style = "" to get the old hardcoded behaviour where all units/cities simply disappear.

Paradrop optionsEdit

It's now possible to allow paratroopers to land on transports. To get the old hardcoded behaviour where they could only land on cities/bases, use paradrop_to_transport = FALSE.

Embarg/Disembarg Unreachable unitsEdit

Embarging or Disembarging Unreachable units is no longer possible by default. Just like units able to attack Unreachable units must list Unreachable unit class in targets, units wanting to embarg or disembarg when Unreachable transport is outside native base and not in a city, must list such transport classes in embargs or disembargs lists. To mimic old behavior that units can always embarg or disembarg Unreachable units, just list them in lists of all possible cargo units.