I'm guessing the theory of industrial zones is that you need them, but maybe you can get away without building them in every city. So you put them in a couple cities and let the regional benefits help everyone.
If we were going to re-balance, I'd suggest the following:
-Make the industrial district harder to beeline (give it a more challenging eureka, or give it other pre-reqs)
-Reduce the stacking effects, or, maybe you make factories +2 prod to each city, and if a city is in range of a factory, they also get +20%. So then there is some bonus for being adjacent to 2+ factories, but it's not twice as strong as a single factory. Or maybe something like the factory bonus stacks, but the power plant bonus doesn't.
-Eliminate the science from pop, so that campuses become the main way to get science. Can add other methods to bring in more science (trade routes, harbors, civics)
-Give more bonuses to a harbor district, but tie them more to resources. So maybe the lighthouse gives something like +1 food per resource, as well as half price to buy water tiles. Give the seaport science per resource.
-Give more bonuses to terrain improvements. Farms get buffed multiple times - mines and lumber mills should as well. If by mid to late game mines and lumber mills worked the same as farms, so that each adjacent mine/lumber mill helped each other, that could also help.
-They need to tone down the cash somehow. Especially once you get the +100% commercial district building bonus, suddenly your banks are +10 gold per turn. Those +100% building bonuses should probably be dropped to +50%.
-Theatres should have extra adjacency bonuses. Maybe give them +1 culture per 2 adjacent forests? Or maybe have it based on appeal value - so that a theatre on a breathtaking tile gives you like a +2 or +3 "adjacency" bonus?
-Finally, I think the district cost should be based on era, the number of similar districts in your empire, and the number of districts in your city. Basically, if you want a commerce district in every city, it's going to get more and more expensive to build. So if the base cost is 60, maybe every era adds 15 to the cost, every similar district of yours adds 30, and every previous district you've built in the city adds 30. So if you have an empire of 6 cities, it's going to be a lot cheaper production-wise to space things out. And it will also be more expensive to lay down the 5th district in a city relative to the 1st one, but since at that point your city is a lot bigger, that cost won't be as noticeable.
Do this, and that helps the game a lot. Or, we'll just have to spend a bit more time researching strategies. My guess is encampments might be under-valued - with +6 production and +2 housing from them, that's not actually that much less than the industrial zone (+9 plus adjacency), although obviously if the industrial zone is helping 2/3/4 cities, that gives it a huge edge.
If we were going to re-balance, I'd suggest the following:
-Make the industrial district harder to beeline (give it a more challenging eureka, or give it other pre-reqs)
-Reduce the stacking effects, or, maybe you make factories +2 prod to each city, and if a city is in range of a factory, they also get +20%. So then there is some bonus for being adjacent to 2+ factories, but it's not twice as strong as a single factory. Or maybe something like the factory bonus stacks, but the power plant bonus doesn't.
-Eliminate the science from pop, so that campuses become the main way to get science. Can add other methods to bring in more science (trade routes, harbors, civics)
-Give more bonuses to a harbor district, but tie them more to resources. So maybe the lighthouse gives something like +1 food per resource, as well as half price to buy water tiles. Give the seaport science per resource.
-Give more bonuses to terrain improvements. Farms get buffed multiple times - mines and lumber mills should as well. If by mid to late game mines and lumber mills worked the same as farms, so that each adjacent mine/lumber mill helped each other, that could also help.
-They need to tone down the cash somehow. Especially once you get the +100% commercial district building bonus, suddenly your banks are +10 gold per turn. Those +100% building bonuses should probably be dropped to +50%.
-Theatres should have extra adjacency bonuses. Maybe give them +1 culture per 2 adjacent forests? Or maybe have it based on appeal value - so that a theatre on a breathtaking tile gives you like a +2 or +3 "adjacency" bonus?
-Finally, I think the district cost should be based on era, the number of similar districts in your empire, and the number of districts in your city. Basically, if you want a commerce district in every city, it's going to get more and more expensive to build. So if the base cost is 60, maybe every era adds 15 to the cost, every similar district of yours adds 30, and every previous district you've built in the city adds 30. So if you have an empire of 6 cities, it's going to be a lot cheaper production-wise to space things out. And it will also be more expensive to lay down the 5th district in a city relative to the 1st one, but since at that point your city is a lot bigger, that cost won't be as noticeable.
Do this, and that helps the game a lot. Or, we'll just have to spend a bit more time researching strategies. My guess is encampments might be under-valued - with +6 production and +2 housing from them, that's not actually that much less than the industrial zone (+9 plus adjacency), although obviously if the industrial zone is helping 2/3/4 cities, that gives it a huge edge.
