(Other ways to weaken a strong defender in CtGW are reducing its efficiency by continuous Fighter attacks or by cutting off supplies due to encirclement.)
Factory costs are defined in file "game_ammunition.lua".
Code: Select all
function GetAmmunitionFactoryCost(faction) local cost = 8 * (faction.luaData.factories + 1) return cost end
The grand campaign runs from 1914 to 1918 for 118 turns. Imagine starting in turn 1 without any ammo production.
Buying the 1st factory for 8 PP in turn 1 results in +1 Ammo per turn for the remaining 117 turns, that is 117 Ammo for 8 PP or 1 Ammo for ca. 0,07 PP.
Buying the first 5 factories for 8 + 16 + 24 + 32 + 40 = 120 PP results in +5 Ammo per turn for the remaining 117 turns, that is 585 Ammo for 120 PP or 1 Ammo for ca. 0,20 PP. This allows an Artillery strike (10 Ammo) every second turn which costs 10 x 0,2 PP = 2 PP.
Buying the first 10 factories for 8 + 16 + ... + 80 = 440 PP results in +10 Ammo per turn for the remaining 117 turns, that is 1170 Ammo for 440 PP or 1 Ammo for ca. 0,37 PP. This allows an Artillery strike (10 Ammo) every turn which costs 10 x 0,37 PP = ca 4 PP.
Imagine now starting in turn 1 with already +9 ammo production.
Buying the 10th factory in turn 1 for 80 PP gives additional 117 Ammo for 80 PP or 1 additional ammo per turn for 0,68 PP. The 10th factory at turn 1 allows 11 additional Artillery strikes during a game which each cost about 7 PP.
80 PP is equal to 4 Infantry Units, so maybe the purchase of the 10th factory is delayed. Purchasing a factory later in the game reduces the number of turns in which we can benefit from the factory, e.g. buying the 10th factory in turn 60 gives only 58 instead of 117 Ammo but costs the same 80 PP, that is additional 58 Ammo for 80 PP or 1 additional ammo for 1,38 PP. The 10th factory then would allow only 5-6 additional Artillery strikes which each costs about 14 PP.
Buying the 20th factory in turn 58 for 160 PP gives 60 Ammo or +1 additional ammo per turn for 2,67 PP each. It allows 6 additional Artillery strikes which each cost about 27 PP (which is more than a new Infantry unit if you neglect the upkeep). (-> diminishing returns)