I was observing this place for a while and now I'd like to discuss something with you.
Looks like for a mobile game to have millions of downloads is not yet a commercial success. As discussed by the article (see the link below) in-game purchase systems often generate more revenue than one-off payments for downloading a game, and it’s a trend already.
If you are using an in-game purchasing, then (assuming the game itself is free to download and play) you allow gamers to get involved right away. If gamers get familiar with the gameplay, fascinated by characters or attracted by any game element used in the game, their willingness to pay is probably increasing. In contrast to that – user’s willingness to pay for downloading a game might be lower, as they did not experience it yet and maybe do not even know what to expect from it.
Another good point is that in-game purchasing allows user to spend smaller amount of money comparing to payment for app download. It is easier to say bye to 10 cents than to 10 dollars even taking into account the value that you get in each case (i.e. some perks in one case and complete game in another). Moreover if a person makes at least one in-game payment, then it might be easier for them to make another one, especially if they really enjoyed their first purchase.
At least such is my opinion and it would be really interesting to compare it to what industry professionals think.
Thanks a lot!