Well done Alpaca for this mod
, this is one of the mods that I classify as Quality rather than quantity Mods. Many interesting ideas and approaches in your mod and they are really appreciated.
I didnt test your mod before, I just downloaded it yesterday (I rarely play or test mods)
Anyway I have few notices to consider:
This one is risky , I had the intention before to do Custom Missions but I canceled this Idea because I know I cant make the AI use the new mission. Now if you replace the Mission effect in lua for ActivePlayer do you expect that the AI will be able to use it? of course not.
So for example, the Great Scientist gives beaker instead of discovering tech, but the AI mission for great Scientist is still discover tech, which will lead to great advantage for the AI. Similarly if the new Mission is stronger that the default it will be Great Advantage for the Human player.
For any change in Gameplay you must guarantee that the AI can use the new gameplay elements otherwise it will be a flaw.
City maintenance is a great addition I had similar idea before. I think you need to reduce the maintenance cost though, if like I understand the maintenance = N, then at city number 20 it will be 20 Gold, and total maintenance for all cities will be 210 Gold per turn which is way too much.
May become imbalanced at late Eras, I noticed some high units maintenance in your mod at modern age (like 15 gold for modern armor) I think that units maintenance should be lower than vanilla so I suggest that max maint for any unit do not exceed 8 gold.
Thats what I have for now.