In my current game (deity, GEM, Eons) I'm halfway thorugh the modern Era and I must say: I like what I see!
- My Cities are HUGE (alomost all, even the Canadian Island ones are 100+, which is well over 10m inhabitants). This is mostly due Corporations (I think they need to be tweeked)
- My cities suffer in crime (1000+ despite 5 Guards per Town), Disease (not sure how much since I don't really care about it), Water (800+) and Air Pollution (1100+). Nice! If I had Revolutions on my Empire would be totally screwed
- Even though disease and Pollution is totally out of conrtol, almost no city (maybe 5 from 134) is

; but most of them are

with 80-120

! So we probably need to increase the

you have by then a bit. But I think in modern cities in a developed world, there is much more

then

so that's actually a bit realistic. Not sure hof it is in such 10m+ Megacities.
- Turntimes are quite ok (~5min) and I haven't had a MAF since the Renaissance (100*100 Viewports and Graphic Pageing)
What I dislike:
- My only remaining Enemy, Ashoka controlls basically everything that is not North and South America - even Hawaii. He has 297 cities. In the beginning of the modern age, he needed always 1 or 2 turns less per tech then I did. Which was 50% of the time. Now I research new techs in 4 turns when he needs 5, eventhough the has more then twice as many cities then I have. And he runs on 100% research, of course (money is not an issue...)
- Money is not an issue! I make about 200k

each turn. If I let a wonder be build 1 turn and then rush it, it's like 300k

at max. WAAAAAY too cheap! If I want to buy a new tech from Ashoka, he only wants 400k

AT MAX. WAAAAAY too cheap! When I trade an equal tech for a tech from him, he demands only 50k

so most of the time I'm able to buy his new techs for nothing but gold. He needs to learn how to buy techs (from other AI) or how to use his gold to rush wonders and buildings
- I get all wonders I want, because I rush them. No problem there.
- He has 297 cities and tries to invade me from time to time (ok, I have basically no troops). But two world powers with all resources, enough food, a stable relationship for many many years should not go on war "just because" at that time.
- Buildings take around 2-4 turns for older ones and new ones 5-10 in my top 50% cities. But I have the Powercomplex (+200

in every city) and Mining Corporation. And Techs only need 2-4 turns...
- It's time we get a Space mechanism working... There are a lot of boring space techs
- Some older buildings like Theorie of Everything, Cloning Lab, Missile Lab... needs to be adjusted a bit. And some Tech/building/resource requirements seems to be wrong. It's time that more peoble reach that point of the game!
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If you are interested, I can upload a Savegame!