Image 1 - A-Train 3D

You are the president of a train company, and you can build rails and get people from stations to stations. Creating flow of people between the stations will grow the surroundings of the stations, and make or grow the city around each station. Of course, to grow a city needs materials, thankfully you can bring those using the same rails too. As each surrounding grows, you will eventually see the installation of building or department stores, making more people use the train and making more profit for your company.