How about a level editor? It would be great to add a part of the game with: river making, start items (tunels, lines etc.), lines colors and the placement of the stations.
This is something that has been discussed in the past and is going to discussed more in the future. It would take a lot of work to have it functioning in a way that we’d be happy with, so we will need to consider it carefully once we get our next update completed.
Glad to hear you’re excited about the idea though!