The prerequisite system has been enhanced in several ways. New flags are described below, and an issue has been resolved with regard to upgrades as prerequisites (see BuildingType Upgrades Are Not Viable Prerequisites).

Require Theater

[TechnoType]►Prerequisite.RequiredTheaters= (list of theater names)

The map theaters in which the type is available. Defaults to all theaters. For example, if only the SNOW theater were specified then the type would only be available on arctic maps. This allows you to implement, for example, the AlternateArcticArt functionality used on the Navy SEAL, but for all types and all theaters (however this may present challenges for your AI). The theater names are:

  • TEMPERATE - most maps
  • SNOW - arctic/snowy maps
  • URBAN - some city maps
  • DESERT - some desert maps, older maps use Temperate
  • LUNAR - Soviet Mission 6
  • NEWURBAN - most YR urban maps


PrerequisiteOverride does not override Prerequisite.RequiredTheaters.

New in version 0.1.

Negative Prerequisites

[TechnoType]►Prerequisite.Negative= (list of BuildingTypes)

The buildings that preclude construction of the type. If the player owns one or more of the buildings on this list then the type will not be available. Defaults to none.


PrerequisiteOverride does not override Prerequisite.Negative.

New in version 0.1.

Multiple Alternative Prerequisites Lists

Ares supports more than one prerequisite list. Each prerequisite list acts as an independent copy of the existing Prerequisite flag, and a minimum of one of the prerequisite lists must be satisfied for this type to become buildable.

For example, if you set Prerequisite=GAPILE,GATECH and Prerequisite.List1=NAHAND,NATECH then the object will be available to any player who owns both an Allied Barracks and Battle Lab, or a Soviet Barracks and Battle Lab.


Either Prerequisite or Prerequisite.List0 has to be specified, because these are only additional lists and the original prerequisites list is still used. If this is ignored and the list is left empty, the object will become always buildable, because an empty list is always satisfied.

[TechnoType]►Prerequisite.Lists= (integer)
Specifies how many extra Prerequisite lists complimentary to the one default list are available. Defaults to 0.
[TechnoType]►Prerequisite.List#= (list of BuildingTypes (where # is the 1-based index of the prerequisite list, the maximum specified by Prerequisite.Lists))

The BuildingTypes required to satisfy this prerequisite list. Each list is checked on its own, and if any list is satisfied, the Prerequisite requirement is satisfied.


Prerequisite.List0, if specified, overrides the existing Prerequisite flag.

New in version 0.1.

Require Stolen Technology

[TechnoType]►Prerequisite.StolenTechs= (list of integers)
The list of stealable technology types that must be stolen before this object can be built. See Stolen Technology for more information.

New in version 0.1.

Require Factory Built By Country

Satisfying prerequisites can be tied to the initial owner of a factory building. The initial owner is the player who owned it first: the player who built it, or the owner of buildings pre-placed on the map. For neutral structures, this would be the neutral country.

[BuildingType]►FactoryOwners.HasAllPlans= (boolean)
Whether this building provides plans for all factory types of the initial owner. If yes, this building satisfies FactoryOwner requirements of all object types. If the building is lost, the plans are lost. Defaults to no.
[BuildingType]►FactoryOwners.Permanent= (boolean)
Whether a player capturing a building of this type would permanently gain all plans of its initial owner. Supported on upgrades. Defaults to no.
[TechnoType]►FactoryOwners= (list of houses)
The list of countries whose factories can build this object. If empty, every country is allowed to build this object. Otherwise, players need to own at least one factory built by a country in this list or the plans of at least one of these countries to produce it.
[TechnoType]►FactoryOwners.Forbidden= (list of houses)
The list of countries whose factories cannot build this object. Players owning only factories built by countries in this list and only having plans of these countries are prevented from producing it.


AI ignores FactoryOwners and FactoryOwners.Forbidden on buildings, but not on units.

New in version 0.6.

Changed in version 2.0.


Below is a flowchart of the current prerequisite system. Blue sections are unchanged from the original system. Pink sections have been modified or added by Ares.

Flowchart of the current prerequisite system

Generic Prerequisite Groups

You can now create custom generic prerequisite groups like the existing POWER (PrerequisitePower), FACTORY (PrerequisiteFactory), BARRACKS (PrerequisiteBarracks), RADAR (PrerequisiteRadar), TECH (PrerequisiteTech) and PROC (PrerequisiteProc and PrerequisiteProcAlternate) groups.

To create new groups simply include the new [GenericPrerequisites] section and add flags with the format GROUPNAME= (list of BuildingTypes). For example:


If you declare any of the existing groups (POWER/FACTORY/BARRACKS/RADAR/TECH/PROC) then the BuildingTypes specified in the [GenericPrerequisites] section will be used instead of those specified on the original PrerequisiteGroup flags (i.e. [GenericPrerequisites]►POWER=, if specified, overrides [General]►PrerequisitePower=). Take note that [GenericPrerequisites]►PROC= does not override or nullify [General]►PrerequisiteProcAlternate=.

New in version 0.1.

Alternate Prerequisites with Non-Buildings

To support the Slave Miner as prerequisite, Yuri’s Revenge added the option to satisfy the PROC requirement by either owning the deployed building or alternatively the undeployed Slave Miner vehicle. This was done only for the refinery group by adding [General]►PrerequisiteProcAlternate=, which accepted one VehicleType.

Ares adds alternate prerequisites support for all Generic Prerequisite Groups and expands this feature to support multiple items of arbitrary TechnoTypes.

[General]►PrerequisiteXAlternate= (list of TechnoTypes)

A list of types that alternatively satisfy this requirement if player does not own a building from the [General]►PrerequisiteX= list.

Replace X with a key from [GenericPrerequisites], first character upper case, all others lower case. For instance, NAVALYARD from above would become Navalyard.


Using BuildingTypes is not supported and adding them here might give unexpected results. For example, upgrades will not work.

New in version 0.B.