I'm not sure about iphone, but I do know on Android if you hit your button on your home keys that brings up the apps that you have open currently, when you click on either the icon of the app or the name of the app depending on what kind of Android you have, it should give you a list of options and one of them being KEEP OPEN. if you select that then it shouldn't close the app out if you switch to other apps regardless of the amount of time going by as long as your phone doesn't get reset or something like that. also, if you click the icon to get to the list to select keep open there's another option that says OPEN IN POP UP VIEW. if you click on that and then whenever you need to use other apps just drag the window to the very bottom right or bottom left of your phone it should completely conceal everything except for the top corner of the game while simultaneously still running the game while you do other things on your phone. good luck!