It seems to be based not only on the physical features of Stockholm, but also the real life Stockholm metro, which is branched. The green line IRL has only one western branch but three different southern going to different areas, but is still known as "the" green line. The red line has two northeastern and two southwestern. My tip is to see the current map of the "SL-system" before playing. The black rail line represents the commuter rail also existing IRL

Is the green the only one color in the world? Why did you do the 1st 3 lines with the same color?

fun map, it comes with permanent train lines which are my favorite kind of map.
The train line colors are far too similar to each other which is a bit confusing, but neat