I picked this game up recently. Game is really fun. Still playing it. I see quite a few places for improvement, not sure how far you plan to take this project..
- It needs a settings/audio menu to adjust in-game.
- Some new terrain and weather would be a good idea to the scene. Maybe snow and leaves falling.
- Would be nice if the upgrade system made visible impovements to the train.
- The random events during movement are funny, and audio could possibly add to it.