Since Firaxis added rioting or something at -20, I feel it's unnecessary now
Emigration is sufficiently different that I don't think it belongs in a core balance set of mods, though it would be cool if that were still a separate, compatible mod that some people could also activate.
Of course, I'm biased, since its not a mechanism I enjoy, I think population should only come from food, not happiness.
I think it might be better to start off RAs at 200 (in classical... you can leave off describing the ancient era cost for obvious reasons ) and double it per era
I'd support this.
Of course, we'd have to do an AI check, to make sure that the AI doesn't still blow through all its gold on RAs. Not sure if the diplomacy AI has a good cost: benefit calculator.
But maybe it wouldn't matter, since once RAs get up to 800+ gold the AIs might not have enough gold stored to use them. Though maybe that's also not a problem.
Yeah, that's why I quoted Marekb's suggestion. To summarize:
Add X% of combined /turn from both civs to a pot.
X% drops with each agreement signed (like the scaling of golden ages).
When agreement expires, split the pot 50/50.
Makes tech diffusion unnecessary.
Eliminates capability to exploit RAs through micro.
Equally affects isolated (mostly late-game RAs) or crowded (early-game RAs) start locations.
Sounds a bit too confusing. The free tech is much easier for the player to figure out and deal with, and the cost is up-front rather than ex-post, so I'd tend to go the cost-adjustment route instead.
However, can you make the cost differ for the different players depending on the era of each player? So if I am advanced and you are backward, I pay a lot and you only pay a little when we enter an RA?
Cons
Militaristic track catches up in the late game (once the resources obsolete for military).
(What other drawbacks?)
Potentially much harder to balance; how do you balance allowing an elite, superior unit vs allowing a superior building?
If there are enough strategic resources on the map to allow a player to get some of each, it might be stronger for them to just build their entire army out of elite units instead.
Potentially: AI constructs the buildings in sup-optimal cities, weakening it relative to the human.
AI can't intelligently sell the building to free up resource access.
AI could be tricked into constructing the buildings with a resource gifted for X turns, then have its military go into resourceless shock (negative iron, -50% penalty) when the trade period expires.
AI unable to intelligently prioritize between units and buildings; spams lots of buildings and locks itself out of units, or vice versa.
I think it might be better to just have the resources for units in most cases (exceptions: uranium offer military vs space-race vs economy advantages in the very late-game, where these downsides don't matter much, and coal for factories), and then if you have more resources than you want, you can trade the rest away for gold, and then use that extra gold to buy other stuff you want to boost your economy.