everything is subject to change. this is an outline, not a final draft
About units/civics it would be helpful if you would post full tech tree with indication where those units/civics are. Tech tree presumably changed somewhat because I can't find steel working in downloaded excel.
If you don't mind some more feedback about various things:
Sea/coast currently have 1f/1c with fishery this goes to 2/1, that means that I usually use only seafood titles. There is no point to using water if I need build more health/happiness buildings. I changed it to 1/2 for coast, and lighthouse/harbour gives +1 commerce for water titles. Sea ports were usually biggest cities providing most trade, currently they have same amount of trade routes as land cities. This solutions allows you to get some serious commerce from sea, but you must build infrastructure to do this.
With change to farm plains are in same situation its 2f/1c title. That's problematic because for example before plough Babylon tops at 9/10 pop if you want some non slave production ( 3xbrickworks, wheat, cow, rest cottages). Some cities become unviable because of this. More floodplains on map? +1 hammer on plains?
I have spoken before about windmill, currently it's useless. If you don't want hills give production just remove it. Watermill + croosbow are good enough for machinery.
One crazy idea that I have is removing all inherent bonuses from resources. You want health from wheat/barley/rice/sorghum? Build granary. Happiness from gems/gold/silver - jeweller etc. This would greatly incentivise tall play as opposed to currently going as wide as possible.
Foundry is bugged it's add iron resource bonus multiple times. I changed it to simple +25% production. Works properly like that.
On Nile river there is single flood plain that's is not on river, 1N of gems.
Would it be possible to code research price increase as +3% for each city above first? Those poor 2-3 city civs are already terribly weak. That way they at least have chance in tech race.
On other things I tested game with bringing it back to civ 4 vanilla config (mining hills, plains +1hammer etc.) well with exception of cottages, I don't know where is minimal distance between them python/dll? pro: AI knows how to play that it's build proper stacks and infrastructure. Cons: UHV becomes childplay, you exhaust build list way to fast. Perhaps I should double price of buildings and add +50% to units? Does this mod is intended as marathon speed (1200t)?
New buildings would be greatly appreciated.
Jeweller - +1 happy from gold/gems/silver +10% gold, 80h, forge loses this.
Water well - it's possible to code city to act as source of fresh water?
Amphitheatre +1happy 80h.
Rename hospital to Infirmary, 3 health.
Harbour- additionally +1commerce from water titles.
Foundry- simple +25% production bonus.
There is good graphics for stockyard/smokehouse, public baths, Infirmary in DoC and FFH2.
Some civs having conditional spawns would be good thing. If Seluicids are stable then no Sassanids for example.
Huh, that bit longer than I thought. As always those are only suggestions that you are free to disregard if they conflict with you vision.