While World Warfare is free to play, we do offer the option to purchase in-game currency (Diamonds) for real money. You can make these purchases through the in-game shop. These purchases are handled entirely by the iTunes store and Google Play in order to ensure maximum safety of your personal and financial information.
It is very important for us to give our players the ability to choose how they would like to play the game - so every area of the game is equally accessible to players as they level up, regardless of whether they invest real money into it or not.
If you would like more information on how to enable, or disable In-App purchases, please check this article. We hope this system provides players with the freedom to choose which play-style suits them.