Butting in on the discussion on Slavery, I have to agree with Charles555nc's opinion that its effect is really powerful, and in my experience (from reading strategies, stories, and educational AARs) immortal and deity players rely on it to an egregious degree.
It's given me quite the headache when balancing civics actually, especially because historically appropriate civic use was an even more important concern for me, and its effect is good enough that you are likely to want to continue using it until well into the late game.
Actually there was a point where I considered removing population hurrying altogether, but I think it's just a too interesting mechanic that connects with many other aspects of the game and makes the early eras much more interesting, so I decided against it.
I had similar concerns with Hereditary Rule which I nerfed by associating a hard cap with its military happiness. This actually was quite useful to weaken Slavery already because its main drawback is the unhappiness, which is most effectively countered by stacks of cheap warriors to produce happiness.
Another kind of broken aspect of Slavery that I've seen abused a lot is that its unhappiness penalty is unrelated to the amount of population sacrificed. This means it is more efficient to use Slavery for expensive buildings and letting the overflow go into cheaper units which can then be finished with regular production. This has the additional benefit while the population recovers, it is more likely that the happiness penalty has worn off. So you can get the same production with almost no downtime, thereby avoiding one of the costs you are supposed to pay for the use of slavery.
To counter this, I scaled slavery unhappiness with the amount of population sacrificed. Every two population points after the first one creates an additional unhappiness (so 1 for 1-2 pop, 2 for 3-4 pop and so on).
I've found that these changes combined encouraged a much more restrained use of slavery, without limiting its strategic and economic use cases (rush building units in case of emergency, productive population control) too much.
It's given me quite the headache when balancing civics actually, especially because historically appropriate civic use was an even more important concern for me, and its effect is good enough that you are likely to want to continue using it until well into the late game.
Actually there was a point where I considered removing population hurrying altogether, but I think it's just a too interesting mechanic that connects with many other aspects of the game and makes the early eras much more interesting, so I decided against it.
I had similar concerns with Hereditary Rule which I nerfed by associating a hard cap with its military happiness. This actually was quite useful to weaken Slavery already because its main drawback is the unhappiness, which is most effectively countered by stacks of cheap warriors to produce happiness.
Another kind of broken aspect of Slavery that I've seen abused a lot is that its unhappiness penalty is unrelated to the amount of population sacrificed. This means it is more efficient to use Slavery for expensive buildings and letting the overflow go into cheaper units which can then be finished with regular production. This has the additional benefit while the population recovers, it is more likely that the happiness penalty has worn off. So you can get the same production with almost no downtime, thereby avoiding one of the costs you are supposed to pay for the use of slavery.
To counter this, I scaled slavery unhappiness with the amount of population sacrificed. Every two population points after the first one creates an additional unhappiness (so 1 for 1-2 pop, 2 for 3-4 pop and so on).
I've found that these changes combined encouraged a much more restrained use of slavery, without limiting its strategic and economic use cases (rush building units in case of emergency, productive population control) too much.
