Pretty cool idea! However I wish there was an undo button in the shop... Also I bought a turret and it didn't show up? Can I only have 1 of each turret type? Also I exited the shop with no cargo and no money to pay for cargo, so I couldn't attach my carriages together, and when I exited I just left with the head of the train.
It's a shame, but great job regardless, really cool ideas and fun to be had!!
If you get a chance to check out my game, that'd be appreciated! :)