Tiny Rails (iOS) - Completed
There are various train engines you can unlock throughout the game by completing objectives. I went with the Behemoth engine you get for completing the game. The carriages I have all match the engine so I get bonuses for cargo & passengers. Each station you visit require a certain cargo which if you deliver gives you gems you can then use to fast track your upgrades (these have a time limit to unlock).
Europe will apparently be added in a future update but once you have completed the campaign story there is not much else left to do except complete the cargo wanted for each station to get 100%, that is not for me I have enjoyed the time spent playing with Choo Choo trains.