There are three main visible stats in the game: Girl’s Friendship, Girl’s Horniness and Money. You can see them at the top right and left corner of the screen. There is also one hidden stat and that is how horny you are. Based on these stats and your interaction with enviroment the story paths unfold.
For you to be able to install this game, you need to enable (allow) the installation of applications
from unknown sources (Unknown sources) in your phone settings. Usually the item is in the Security section.