Objects in the game - terrains, units, buildings, improvements, etc - differ by their stats, but what makes them truly different mechanically are their special abilities, or as we call them - *Uniques*.
Each game object can have any number of these Uniques.
The different possible types of uniques are available [here](../Modders/uniques.md), with each unique having a string value, e.g. `"Gain [amount] [stat/resource]"`
These are unique types, because they are in fact *templates* for possible *concrete* uniques, where the parameters in square brackets are filled in with specific values - e.g. `"Gain [20] [Gold]"`
Game objects should have *concrete* uniques (parameters filled in)
Every parameter in square brackets, is defined by its type, a list of which is available [here](../Modders/Unique-parameters.md) - each parameter type has its own text value, e.g. "amount" means an integer.
That determines possible values that this parameter can contain, e.g. "amount" should only contain strings that can be serialized as integers.
Concrete uniques that contain *incorrect values* (e.g. `"Gain [three] [money]"`) are warned against in the mod checker, and if they're serious enough, also when starting a new game with the mod
Uniques can be modified to do certain things, using special Uniques that are shown in the [uniques list](../Modders/uniques.md) within `<these brackets>`.
This is done by adding these modifiers after the unique like so: `"Gain [30] [Gold] <after discovering [Steam Power]>"`
The most common type of modifier is a conditional - basically limiting the unique to only apply under certain conditions - so all modifiers are sometimes refered to as conditionals.
Most uniques are long-term effects - they apply as long as you have the object containing them (building, resource, tech, policy).
Trigger uniques are different - they are one-time effects, but which may be triggered several times.
Trigger uniques come in two flavors - [civ-wide triggers](../Modders/uniques.md#triggerable-uniques) and [unit-wide triggers](../Modders/uniques.md#unittriggerable-uniques).
Unit triggerables are only relevant in the context of a specific unit, so they can be attached to units, promotions or unit types.
Any triggerable unique added to a unit which has [unit action modifiers](../Modders/uniques.md#unitactionmodifier-uniques) will be considered as a unit action.
Unit actions can contain civ-wide effects as well.
Trigger uniques specify their activation with trigger conditions.
Like the triggers themselves, these come in two flavors - [civ-wide conditions](../Modders/uniques.md#triggercondition-uniques) and [unit-wide conditions](../Modders/uniques.md#unittriggercondition-uniques).
Trigger uniques with no trigger modifiers are activated upon construction (units, buildings, improvements) or discovery (techs, policies).
Events are a ruleset object that act as a sort of "extended trigger" - they are activated by the `"Triggers a [event] event"` unique, and they trigger other uniques depending on user choice.
We parse the unique by comparing the string given by the modder minus square bracket contents, to the known list of uniques.
If we find a match - Congrats, we set that as the unique type.
When we check for uniques in the code, it's always for uniques of a specific type, so we can just check the 'unique type' we previously assigned
We then take the parameters of that unique, which we also determined previously by scanning for all strings within square brackets, and use their values in determining the effect of the unique
There is a LOT of caching involved everywhere to make this all as fast as possible, but you really don't need to worry about that, that's my job ;)
