@ Goblin
If your looking to make your SS campaign 2tpy i highly suggest checking out my sig. I have put together a 2tpy mod for Stainless Steel. I am still working on it, but in its current form it is certainly playable. In the post regarding it there is a lot of discussion on how to improve it and may help you mod the game more to your liking.
With that said, Augustus Lucifer's suggestion of editing the descr_settlement_mechanics.xml is your best way of reducing income (across the board, for you and the AI). Keep in mind though, there are a lot of balancing issues that can come into play. I have done quite the extensive research into this file and can help you understand it better (feel free to PM me). I should post my findings elsewhere on these boards for the community as the file controls many aspects of the game.
For example. Take this simple part of the file.
Code:
<factor name="SIF_FARMS">
<pip_modifier value="0.75"/>
</factor>
SIF = Settlement Income Factor
You will also find SOF and SPF within the file - Order and Population factors respecfully.
SIF_FARMS refers to the Income that each level of farms built will bring to the settlement.
The pip_modifier is different for every single entry in this file. Most often it refers to a value in the EDB. In this case it refers to the level of farms in the EDB. Being;
Code:
capability
{
farming_level 1
}
The SPF_FARMING_LEVEL further up in the xml file refers to a value in the descr_regions.txt file found in world/base folder. It can become confusing as this file is very detailed (although very simple layout).
Additionally, The actual value for the pip is different depending on whether it is a SPF, SOF or SIF pip.
Generally speaking each pip carries the following weight (at times these are percentages)... (with a pip of 1.0)
SPF - 0.5
SOF - 5
SIF - 10
The pip_modifier directly affects the value of the farming level in the EDB.
Adding the lines
Code:
<castle_modifier value="1.0"/>
<city_modifier value="1.0"/>
Will then modify that value further and change the way Farms work for city and castle.. It is kind of detailed.
Another example...
This will change the rate of population growth based on the number of buildings present in the settlement, BUT only buildings that give a bonus of some kind will have an effect. Bonuses include any bonuses such as law, happiness, farming level, mining level etc etc.
Code:
; SPF Buildings directly affects ... only some buildings grant 0.5% per 1.0... any bonus given from EDB (1 per building)
<factor name="SPF_BUILDINGS">
<pip_modifier value="0.34"/>
</factor>
Once again, this file carries with it alot of balancing issues where other files come into play. You need to understand what each pip is actually affecting to accuratly increase or decrease a value. I have figured out most of the values but some still elude me such as Triumph. Others are also (as far as i know) hardcoded and can only be edited in this file, such as Boom. Most pip values though refer to another value in another file. Such as the Farming level in both the EDB and regions.
But, yeah, back to your question, check my sig
Hope it helps.
EDIT: I would also like to point out that in some EDB's the bonuses granted form one tier to the next are the same, meaning the following tier building actually grants no additional bonus. Which makes certain tier buildings nothing more than a stepping stone or to gain the benefits of better walls or recruitment options. - which may be the mods design, or could be a misinterpration of the values.