Nice game, very cute, the controls are quite intuitive and the rules are easy to catch on.
I just didn't understand the purpose of rewinding but apart from that very nice game.
Hello, thanks for your comment !
The coal capacity (the black progress bar on the side of the train), is the trading item to be sold to houses
The train has a coal capacity which get consumed by reaching a house. If the train doesn't have enough coal, it does not collect the money until it refuels at the factory.