Yes, altho I am welcoming feedback on this mechanic. I'm half tempted to just cut the cost back to what it was before Firaxis doubled the cost. I guess they were thinking everyone runs the Colonization policy (+50% toward Settlers in the unmodded game) but I am not a fan of that mechanic because I think it shoehorns a period into the game where Settlers are cranked out like a factory.
As of one of the more recent Tweaks patches, you get 10% toward Settlers for each building in the city center. This includes the Palace, so the capital always builds Settlers 10% faster, and also Monuments, so Rome is also naturally 10% faster due to the free building (fits with their ability set and agenda). Walls, Ren Walls and Star Forts are also included, since those are also built in the city center.
Not sure. I havent looked much at alliances.
Long post below, sorry. Love your mod, been playing it since you first posted it. Appreciate it a great deal, and it is along the lines of Thalacicus mods from Civ5 - the vanilla game is boring and easy without it. Nevertheless, I am a little concerned about the situation with settler production, thus my first post with Civ 6 mods (have played civ since Civ net, so long ago).
I play on a gigantic map, island plates, marathon speed, at Deity. Even if I build a monument, encampment to get the barracks and then walls in the centre, and even purchase a granary, by that stage city population is up to between 5-7 in most games (and imagine you have few resources or no amenities or only those requiring irrigation), and a settler will still take me between 40-70 turns to build. In the meantime, the AI civs already have 3-5 cities when it is even reasonable to start constructing my first settler.
Depending on starting location, one could need multiple other builds. This is one example of many:
'You are no where near a coast at the start, meet no other civilizations or city states, and have almost no tribal villages - combined with reduced science and culture in hardcore, by the time the first settler is built to construct a galley to meet a civ or state, you are so far behind in all aspects. It is the luck of the draw - if you have a scientific city state or some tea nearby, maybe you can compete having only one city. (further, with no eureka for writing to build a campus to get the extra science to keep up, this further delays any expansion).
When you do start meeting other civs, you are immediately denounced for being weak and small, unless you are just building units with no place to go and increasing turn costs). From that point, the only cities that can build settlers to mid-game is the capital (the coast is trying to build a couple of ships, and the capital is then stuck between a decision on progress or expansion).
Finally, if you play with Pericles with the extra wildcard spot, in the above scenario, the extra spot is fairly useless (no need for extra combat, scouts do not need the buff since there is no land to explore, and +1 culture for cities without a monument is useless until you can actually get that first settler built. In the end, the only useful policy is +1 faith, +1 gold in the capital from Code of Laws. From there the next set of policy options are not particularly helpful if you still have not met anyone, except for Mysticism.'
In short, the latest patch and the QUO changes to setter production, it seems to me, make every game the luck of the draw on starting location, while before the patch and latest QUO changes, at least there was a chance from any start location. It is just my take on it - I have been playing on watery worlds since civ 3 (the naval aspect is interesting), and the challenge should be creating the best strategy to win given your starting conditions, not on the luck of your starting location (now I know immediately within 20 turns of my warrior walking about whether or not I even have a chance at winning when I realise I cannot expand to at least 1 other location early - all units except scouts cannot embark until Shipbuilding!).
Maybe just reduce the costs of settlers overall? It think is not fun to play with a single city or only 2 cities so far into the game, in the same way the AI would build only 1 or 2 cities max, when playing with AI+ mod (now defunct) on watery worlds - it was so easy to eliminate them with only 1 or 2 cities to conquer.
Finally, I think civ has always been about expansion, especially on large maps, which is why it is fun to play. No expansion, little chance of winning.
Cheers.