I spent an surprising amount of time playing this, because I was having a lot of fun. Upgrading your train, changing the constellation of your train "components" and figuring out what to buy/sell and where feels very rewarding! I can easily see this becoming a successful free to play mobile game.
The only feedback I have right now is to balance out the economy - buying a new wagon can throw you back a lot, and economic progression can feel extremely slow. Other than that - great work!
// Florian