App running while not playing?

I have built a mobile game like Adventure Capitalist. Now, I know that one of the requirements of putting it up on the Google Play Store is that you be able to hit esc and close the app. The question I have is: If I implement that, will the game continue to run in the background automatically unless it is "force closed"? Or do I have to script it to do that. And, if the latter, what would the function/comand look like?