Sim City 4 is good. there is lots of sites for custom content. you can have one of your cities neighbor another one of your cities (in a region) there is tools that can create custom building and custom maps (regions) I have two Reshiram shaped maps, one is flat and the other, the altitude is based on what Reshiram looks like. here is an example of a map pack I created
http://community.simtropolis.com/fil...mon-maps-pack/