It will probably be an easy one too, since the game can apparently run "for a few minutes" without network connectivity so I'm guessing it will be all client si

It will probably be an easy one too, since the game can apparently run "for a few minutes" without network connectivity so I'm guessing it will be all client side with the server just handing storing save files/data etc and real work being client side. This also means it will be possible to hack your city and get it into the persistent world, so if your city affects nearby regions the game will be a mess.