A rather brilliant tactic to climbing the top app list was implemented a while back by a game called "only one life" or something like that. Bsically, you had to delete and reinstall the app to play again. If, for a brief period, players got say 100 grenades or 250 gralats or something every time the app was installed, graal would theoretically climb the top list quite quickly, provided this still works. Oh, and duke, unfortunately purchasing in app stuff doesn't make the app more well known.