It is obviously some goal to create a huge city at some stage...

In my second attempt now, I try to build up one gigantic thing in the middle of a small map. Here is the plan:

Map requirements:
- one city in the middle of the map with no huge lake or something next to it
- good connections to at least two factory chains
- three cities on each side with no connection between the two sets

Idea:
- two stations for transport, each connected to the three cities on their side of town
- any person travelling from the left three cities to the three cities on the right, needs to go through megapolis
- one station for cargo, connected to both factory chains
- ignore all the other cities in regards to city traffic, only my megapolis in the middle gets trams connecting the east station with the west station

What I noticed:
It seems you cannot force the population to outgrow other cities on the map by far. The best I could reach was about double the size of the smallest village.
The transport service between Megapolis and the other cities is very important for grow.

I have to admit that I have no idea how the economics in this game work.

I'm playing my second game, a medium-medium-hilly map. There is one big central valley where my three biggest cities each have internal bus or tram lines and they're all connected to each other by passenger trains as well as cargo lines bringing in goods from three different factory chains.

Every line running in those three cities is making money, but by far my most profitable line is a passenger train between my two smallest towns. Each of those two small towns only has a minimal internal bus line and absolutely no cargo coming in, yet every train is apparently carrying nearly -half- of the population of each town to the other.


I think you may be right about there being a size limit between the largest and smallest town because growth in my largest towns seemed to stall until I developed some infrastructure in my smaller ones before they started growing again.