I'm back again, I'm on T79 now. Migalhone I haven't checked your save yet, as I wanted to reach T90 myself and then compare them. But I stopped here because I wasn't sure where exactly to settle city 7, what mistakes I made and what I could be doing better. Am I building too many libraries? I have my 7th settler in munich ready to move this turn, and I was planning to whip another settler and worker in Berlin and Cologne. Besides that any general thoughts?
Libraries in Munich, Berlin and Hamburg are good choices, since those cities have plenty of riverside tiles to boost cottages and thus your science output. Do note that buildings libraries makes sense on cities that actually produce science, since the bonus science they provide is a percentage based one, so i would hold on building libraries on less developed cities such as Cologne, Frankfurt and Essen: if they produce next to nothing science, no point building libraries there.
You have gold and ivory hooked up right? That means +2
for every city connected to the trade network. Grow those cities, and use slavery to 2-pop and 3-pop whip extra settlers/workers/granaries. You want to keep growing your cities to make use of the higher happiness cap, and you want to build granaries in all cities.
Special mention to Frankfurt: you're building a library there, but its only size 1? Have you connected the clams already (on mobile atm, cant see clearly)? If not, build a workboat. Later on when you get sailing build a lighthouse, to turn those 1F2C tiles into 2F2C, and turn Frankfurt into a decent commerce city.
There are no particular good spots for your 7th city, so i would go for the sugar one, it has less jungle tiles than the bananas one, so sugar city first, bananas city next. Obviously you need iron working to chop all that jungle, trade with an AI if possible. If not self tech it yourself. A 9th city may be available, east of Berlin, near the lake tile: if settled later you'll get double spices, ivory, freshwater and some green tiles. Only consider going for it after sugar/banana spots are settled.
After maths, i would go Alpha-Currency-IW, if not able to trade for IW.
You seem to understand the importance of workers, good! Keep in mind that when settling new spots you'll need workers to improve those cities, preferably not at the expense of the existing cities!
Hamburg seems to have good production, consider using math-powered chops to quickly pump out settlers for the remaining settling spots available.
Overall, nice job grabbing all that land