After being a gamer for years always searching for the next big or even the next good thing I have found the best way to be discovered (if you have a good/wanted product) is an in game advertising on a pay per view design. Many successful games, personally defined as a game with over a million downloads (usually free downloads) use in game advertisements to supplement their game being free. Considering the cost of the in game currency you are awarded for viewing the adds are about 300 views for 5$ it can get your game/app to a lot of people while incurring minimal costs to overhead. You can also set maximum views per day and so forth if you are trying to adhere to an advertising budget. Feel free to call me for more details on this method.