Part of me would love systems like natural resources (mines, quarries forestry etc).
Elections.
Realistic natural environments with endangered animals and natural wonders that you could exploit for tourism or destroy at the cost of fines and lost popularity, protests etc.
Pest problems like locusts, bed bugs and rats.
Starting in the industrial revolution.
Segway cities
But another part hopes they will keep it simple and focus on getting the basics right
My main hope is robust mod support TBH
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