You opened your eyes in a hospital room, and you don't remember anything about yourself. Your past is all lost! Sometimes you're seeing some images and talks in your sleep. They're dreams or not? Where are all these images coming from? Why are you seeing all these images, where are you, and who are all these people? You need to figure out your situation before everything is too late.
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