OK, here's the writeup of the transition from Renaissance to Industrial. There are three techs that can kick off the Industrial Era:
- Military Science
- Photography
- Steam Power
These are the three techs that get my Industrial-1 designation.
This is the list of technologies that make up the Renaissance-6 level (behind the spoiler box):
However, Renaissance goes two levels farther. This is Renaissance-7.
Renaissance-8 is very short, with only three techs.
Photography is not the problem tech here, because it requires Patent Rights (Renaissance-8).
However, Steam Power only requires Replaceable Parts (Renaissance-6) and Scientific Method (Renaissance-4). Part of the problem here is that Scientific Method has gone
backwards compared to BTS. In BTS, Scientific Method is one of the first Industrial techs, and we have put it in the middle of the Renaissance. Historically, the scientific method really takes off in the late 1600's, which is definitely Renaissance.
Military Science has an equal problem, as its prerequisites are Grand War (Renaissance-6), Military Tradition (Renaissance-6), Scientific Method (Renaissance-4), and Team Sports (Renaissance-3). I'm not completely sure what to add here. Rifling would only push Military Science up a little; Steel might push it too far.
The change I would definitely suggest is:
Steam Power
Req Techs: Replaceable Parts AND Scientific Method
AND Patent Rights