Subway Idle 3d tycoon, the idle metro simulator! Subway Idle is all about upgrading and maintaining a subway map for a growing city. Upgrade and connect stations between other stations and get your trains running. As new stations open, earn more money and upgrade your metro even further! Decide where to use your limited cash flow. Be sure to keep your city moving. Multiple cities to progress through! Earn while your offline to advance your metro! Tons of upgrades to advance your network.