You all know SimCity, the management game that lets you manage a city as a whole. But I’m pretty sure you don’t know Simutrans (Transport Simulation) yet!
This free, open source game in French (youpi) is a simulation that works on macOS, Linux, Windows, and BeOS and in which you have to create transport systems between different places. Either by road, by air, or by rail, etc. Bus, tram, planes, truck will say thank you!
You will have to think of the smallest details: Stations, speed limits, level crossing, hangar, mail transport, seaport for your cargo ships, etc., etc. I admit that the grip is not tender but fortunately, there is everything you need to guide you at the beginning with tutorials and docs. Enough to start chasing Anne Hidalgo.
The game can be played alone or in multi via a server that you will need to install. Regarding the maps, they have no size limit and you can terraform anything you want.
As it is open source, different mods and paksets are available to change the design: