You play as Sean. He lived a happy life until everything started to fall into pieces. On top of everything, you have been under close surveillance by some otherworldly creatures with naughty powers. But fear not! As those powers are not exclusive to them. But with great power comes responsibility (etc. etc. etc.). So the question is, what will stop you from using them?
In order for you to be able to install this game, you need to enable (allow) installation of applications from unknown sources (Unknown sources) in the phone settings. Usually this item is in the Security section