I always remove the minimum era requirement from ideologies, since it kind of undermines the whole philosophy behind unlocking them with enough finished policy trees. Units, buildings, improvements, yields...science already has enough going for it in every other aspect of the game. It doesn't need to be a pre-requisite for policies too. That was the idea behind unlocking next-era trees by finishing current-era trees as well.
I don't suppose anyone knows how this is done?
Edit: I'm guessing IDEOLOGY_START_ERA and IDEOLOGY_PREREQ_ERA have something to do with it. Is start era the one that
gives you ideology based on techs and prereq era the minimum before you can
unlock based on policies? If so, then something's amiss, since they're both set to the same value.
I've made a mod that makes policies come super fast (half costs, double free policies from wonders & first/second to ideology, everyone's Poland [and Poland is double Poland]). In CBP, policy trees unlock at 1/2/3 trees completed. I'd like to change it to 2/4/6. I've changed BALANCE_MOD_POLICY_BRANCHES_NEEDED_IDEOLOGY, but there doesn't seem to be an equivalent for unlocking Piety/Statecraft/Athletics or Rationalism/Imperialism/Industry.
Edit: Well, it turns out that the CP/CBP doesn't actually "count" completed trees at all. How it actually works is the Finishers from Tradition/Progress/Authority are set to unlock medieval trees, and in turn Piety/Statecraft/Athletics are set to unlock Renaissance trees. Only Ideologies actually "count" the number of completed trees.
I managed to get around that though. I NULLed "UnlocksPolicyBranchEra" column and added dummy policies that unlock medieval and renaissance trees:
Then I spent a few hours trying to figure out the scary .lua code.

Basically I made a counter that counts the number of finished trees and gives you the dummy policies if you have enough:
I still don't know what IDEOLOGY_START_ERA and IDEOLOGY_PREREQ_ERA do differently than each other though.
