I'm sure this has all been covered before but I'd like to see some of the following (in no real order except for 1 which would be my priority):
1) A globe, like a Google Earth Globe, rather than a cylinder. It would be so much more fun for regular earth maps especially in the late game with flights, ice melt, submarines, missiles etc. And for alternative maps where the poles are desert or something else. Pretty sure they want to so must be tricky. And a decent large earth map rather than relying on modders for this one.
2) Land reclamation. Hill flattening. Hill building. Basically more terraforming in the late game.
2) Languages! Basically a more matrix approach to the civs and changing up the cross functional systems (similar to loyalty, power, appeal) that don't have their own victory type. Like language. Having language spread based on various factors, like population, open borders, religious pressure, trade routes, cultural pressure. When cities start speaking a different language and have a different religion that wouldn't bode well for loyalty. Having other civs speaking your languages gives you a boost to tourism or culture or pilgrimage or whatnot. Similarly if your culture or economy is high then maybe you can assimilate languages and exert rather than take in language pressure. Great works of writing would be in a specific language (as could scientific discoveries), religious texts would be in a specific language and reformations could be in another (i.e. schisms). It would create an interesting layer to almost all victory types. And imagine having your civ leader animation starting to speak their stock phrases in a different language half way through the game.
Currency could be another example. There could be an impact on trade routes or some form of economic victory type. Or health & disease which could affect your army's fighting power or religious belief.
3) Migration - the ability for people to move to places with more economic opportunity or fun, religious freedom, or food, or away from war or a disaster (or even to be expelled) with increasing options as the game goes on. Your policies can decide how open you are to migration (and birth rate in some ideology in the late game...) so you can curate your civ's population slightly better if you have a lot of food, housing, amenities or whatever systems the game will have (or avoid too high a pop if poor or no housing or climate change etc.). I think there's something very interesting you could do with migration & currency & corporate brands (who patent ideas - see below) for some form of economic victory. Migration obviously affects loyalty, religion, culture, language, (and disease?)
4) A pre-civ phase that many have covered, where you can grow from hunting / gathering, to pastoralist to nomadic, perhaps with some civs staying in that mode, like Mongols amassing into migrating hordes rather than settling cities. Domesticating an animal like horses etc. could come before agriculture. Pastoralists can run from war and disease etc and scout much faster, absorb ideas, trade, make tile improvements and pillage...
5) Outposts, towns, then cities with different numbers of tiles etc. Perhaps towns are super easy to take over so borders can change more easily in war even if cities are not taken. Make benefits to towns staying such. Cities can grow more during industrialisation, even swallowing up towns (and potentially becoming megacities with the city centre occupying multiple tiles). Nomads could have relatively sophisticated outposts etc and improved tiles in their territory without a city.
6) More human scientific changes - e.g. air conditioning made tropical living so so so much better. And refrigeration, penicillin. And cars, telephones, subway systems, bicycles, and airports and air travel and shipping should make trade routes and some things so so much faster in the late game.
7) Who owns ideas... It would be cool if science and cultural ideas "spread" from points of discovery per turn or something so they can be picked up (potentially simultaneous discoveries also). It's organic and it means you benefit from being in a civ cluster compared to being isolated. But also disease and languages and religions spread too along these same routes. It's more "silk roady". It would be cool if certain luxuries could be grown in similar habitats after the skill has been learnt (e.g winemaking). Or if luxuries could be sold on between civs who had no way to own or buy (the way the middle east dominated until the Portuguese found their own routes).
Similarly in the late game some scientific discoveries could be patented to companies rather than to a civ, so if you let another civ's company operate in your territory (and they generate science & money for you but also language and culture pressures...) you better hope they stay. Or under some ideology you rely wholly on domestic science and shut out the world. It would be interesting for some type of economic victory and science victory (and would make corporate espionage a thing).
8) Merged districts - it would be good if districts didn't need to be on new tiles but you could stack at least some districts together, especially if there are unique synergistic benefits. So commercial & cultural gives you unique TV studios, holy site and encampment gives you some martial religious order or unit availability etc. It would make cities look more organic and more individualistic at the same time and give more space for tiles to have improvements like farms or the unique civ stuff or suburbs and megacity type stuff. In the late game there are too few tiles - a beach shouldn't take up a whole tile as an industrial centre or neighbourhood. Districts could be moved or reallocated in the late game (e.g. swallowed up by a megacity after you built a subway to it).
9) City state goals to align somewhat with their personalities... war states actually having good armies and sending envoys when you conquer. Civs becoming city states and city states becoming civs.
