Can't play this game longer than 10 mins in a single play b'cuz of the long & irrelevant duration of each mission. Some lasting from 30 minutes to 2 hours, where we can do nothing but let time pass us by. Almost everything useful is under the pay to play. The only human interaction required in this game is tapping at raw material required, while the AUTOMATIC trains are operated without our help - which is the biggest bummer. It's like watching Crypto currency - opening & closing the app.