Reducing AI propensity to build farms?

[civworker]

I find late game that the AI pretty much replaces every non-unique improvement with farms where buildable. On hills, next to rivers, everywhere
As a result, production drops significantly but they have big cities and don't even run communism.

How do I make the AI want to build fewer farms and value mines and lumber mills more?

 

[Laurana Kanan]

Funny thing is I once tried to help a suzerained industrial CS by replacing some of their farms on Plains Hills to mines, which would have also helped their Industrial Zone adjacency. A few turns later they had replaced them with farms again.

Maybe @Siesta Guru might have some insight?

 

[Siesta Guru]

Well internally the way it works is relatively simple.
It always calculates a score for each of the improvements, and then decides which improvement is best based on that.
What's unfortunate is that this calculation doesn't care about a lot of information humans find meaningful, such as trying to find the right balance between production and food.
Basically if it considers the food+housing on a farm more important on one spot, itll consider it more important on all spots.

Modding wise, unfortunately there's not too much we can do about it as far as I'm aware. Usually calculations like these are tied to the desires for the different yields, which you can alter through AiFavoredItems. However, it appears this particular calculation is rather insensitive to these desires or may not even use them at all. I've tried making Gilgamesh stop building his ziggurats all over the place to no effect.
I've not done very extensive testing though, and it may still be possible. A few places you look at:
- Using the 'improvements' ailist system to give a direct boost to certain improvements
- The yield desires in Aifavored items, look for YIELD_FOOD etc.
- The Build City Improvement behaviortree
- Maybe the city specialization favoreditems (BUILD_FOR_PRODUCTION in leaders.xml)
- There might be an AiList system for improvements that could give direct boosts to certain improvements though I can't see it being used in the base game

 

[Laurana Kanan]

Thank you for the quick response! So there's you're answer @civworker .