@civ-clone/core-city
Contains base functionality for the concept of a `City`, including the associated `Rule`s, `CityRegistry` and `AdditionalData`.
@civ-clone/core-yield
A `Yield` is a key element in Civilization and can refer to anything from the `Attack` value of a `Unit` to, the `Food` returned for a `Tile` or the `Unhappiness` produced by a `City`.