I have a suggestion about the Limited Resourses System.
Now crop resourses can supply 1 city, seafood can supply 2 cities, luxury can supply 3 cities, and media can supply 10 cities. It's suitable for Classical or Medieval civs, but not enough for Industrial and later. In 19th or 20th century, there're civs with plenty of cities and a large number of pops, 1 resourse supplies 1 city is outdated. In modern society, the development of logistics makes it possible to share resourses in more cities.
My suggestion is to increase the number of cities that shared 1 resourse when get a certain tech. Here is the concrete plan:
Crop resourses(corn, wheat, rice, potato, millet):
+1 city for Crop Rotation, +1 city for Biology, +1 city for Infrastructure.
Seafood and livestocks(clam, crab, fish, deer, cow, pig, sheep):
+1 city for Optics, +1 city for Refrigeration, +1 city for Genetics(maybe Ecology if Genetics is too late).
Commercial crops(olives, spices, wine, banana, cocoa, coffee, cotton, dye, incense, opium, silk, sugar, tea, tobacco):
+1 city for Horticulture, +1 city for Microbiology.
Luxury resourses(fur, ivory, pearls, gems, gold, silver, jade, amber, whale):
+1 city for Heritage, +1 city for Cosumerism, +1 city for Tourism.
Media resourses(football, movies, singles):
+2 city for Television, +3 city after Internet is completed.
The only resourse I can't range to the 5 kinds above is salt, maybe +1 city for Companies, +1 ciy for Infrastructure.