These are kinda old (pre-adjust on secret societies), but I really felt the impact of the balance on those things in one of my games.
Being the Reformed Norse Scandinavian Emperor myself, I was slightly surprised by what was happening to the Catholic world in the meantime when I was concentrated on the Eastern Front.
Behold the unreformed Suomenusko Emperor of Francia and Germany.
And a little south the Jewish King of Italy.
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In another game I also had the postal system malfunctioning, good for me, less so for the sender:
Also, Aztecs came and were not prepared to face the reformed Roman Empire. Now they're just hanging around in Northern Africa (for over 90 years now), preventing me from getting the "And Stay OUT" -achievement T_T