So I found on the other topics how to use the slavery button. I have Bronze working research. So I should have Slavery. But on my cities I can't activate the "Slavery" button it still says "Slavery needed", so my guess is that I should activate it somewhere... But how do I do that?
I should have enough population to use Slavery btw (I have +9 angry people for overcrowding in the city I want to use it).
When you first research Bronze Working (and other techs that unlock new Civics), a popup screen will appear to allow you to switch to it immediately. If you choose not to do so, you can access the Civics menu by pressing F3.
Yes I did do the revolution. But didn't know about the max population thingy. Apparently that was the reason, I just tried it on a city with less days left for the building it was making, and the button wasn't grayed out :). Thanks for the info ! Really helped me out... I twas frustrating to not be able to use that function.