This page is about extensions, which now have a separate page from the themes. For themes, see Themes.
When starting TrainStation, the Main Station has only one rail for trains and one short street for buildings. You can only dispatch four trains at a time, and you can't dispatch Diesel, Electric, Maglev, or Hyperloop trains at all. Extensions allow you to change all of that.
With Extensions, you can make your station bigger, dispatch more trains, dispatch them quicker, and discover new technologies that unlock more parts of the game. You even can build four more stations and upgrade them too! All together, the game has over 170 extension upgrades available.Special Building named Stock Exchange. Having this building in use at one of the player's stations (not in Storage) will grant a 20% discount to all Extension purchases. Discounted costs are usually listed on the Wikia for each Extension.
Extensions are divided up into five types: