The Lumia 640 comes with the latest version of Windows Phone 8.1, including a new settings app and the ability to hide the navigation bar. The game doesn't display it if I've unhid it before resuming from suspension, so I must toggle it again for it to show. The status bar also doesn't go away on the splash screen, which I assume affects all Windows Phone models since apps have always been able to hide the status bar. In the menus the UI does not scale after toggling the nav bar until you return as well.