FreeUnit

Flag:	FreeUnit
File(s):	rules(md).ini
Values:	Strings: Normal text. (Limited to: VehicleTypes)
Applicable to:	BuildingTypes

Specifies the VehicleType that should appear beside this BuildingType when it is placed after being constructed by the player (the unit comes free with the building). This logic is only used by the two Ore Refineries in the unmodded game.

You cannot have a BuildingType that costs less than its Template:TTL. If the Template:TTL of the Template:TTL is higher than the Template:TTL of the BuildingType, then the price of the BuildingType will be overridden to match the Template:TTL of the Template:TTL.
For example, if you have a BuildingType with Template:TTL and its Template:TTL has Template:TTL then the BuildingType will actually cost 2000 in-game (although note that the construction speed of the BuildingType is not affected by this change in price).

If the BuildingType is sold then the Template:TTL Template:TTL is not taken into account - the BuildingType's Template:TTL is based on the Template:TTL of the BuildingType only, so you need to set the Template:TTL for the BuildingType manually. In the case of the Ore Refinery, Template:TTL is set to 300 because the Ore Refinery has Template:TTL and its Template:TTL has Template:TTL (in the unmodded game, you get 50% refund when you sell a BuildingType).

FreeUnit and Industrial Plant logic

As far as Industrial Plant logic is concerned, 'free units' are not actually free. In the case of the Ore Refinery (Template:TTL), the game thinks you are paying for a 1400 credit ore miner and a 600 credit Ore Refinery at the same time. Assuming the original Industrial Plant settings are used, VehicleType prices are reduced to 75% and BuildingType prices are not reduced. Therefore the price of the Ore Refinery becomes:

(0.75 x 1400) + 600 = 1650

If you changed the Industrial Plant so that BuildingType prices were reduced to 50% as well (or made a new Industrial Plant), then the price of the Ore Refinery would become:

(0.75 x 1400) + (0.5 x 600) = 1350

Note that multiple Industrial Plants stack their bonuses. For example, owning two [unmodded] Industrial Plants would cause the price of the Ore Refinery to become:

(0.75 x (0.75 x 1400)) + 600 = 1387.5

Bugs/Side-Effects/Unexpected Limitations

If you own an Industrial Plant that reduces the cost of VehicleTypes and/or BuildingTypes (whether one or both of these causes the problem has not been established) using a very small multiplier, say 0.01, then FreeUnit will cease to function on all your buildings - i.e. the free unit will not appear.