I'm afraid there isn't. The way android works is to put things into the background when other fullscreen process are running, and when a GM game is in the background, it is essentially paused. You may be able to write (or find) an extension that can get around this, but I certainly haven't seen one. Your best bet would be to have some kind of controller object that stores the time value when the interstitial starts, then gets it again when it ends, and use the time difference to modify the game to make it look like it was running the whole time. Would be a little complex to set up, but I really can't think of another option.