I hope it is ok if I post this, even it's not directly related to RR3. I found a great article from the Commercial Director of Fireproof Games Barry Meade about free-to-play vs. premium games on mobile devices.

Fireproof are the creators of "The Room" and "The Room 2" which I highly recommend to download if you like puzzle games and want to make a break from monkey-racing from time to time. 

It's a long piece but if you're interested, it's really worth a read.

http://www.polygon.com/2014/5/9/5699058/free-to-play-mobile-candy-crush-the-room