The Digital Shadow tool named “Watch Dog” is an alternate reality game which allows the Facebook users to check what things happened in real time. It shows the pictures or the texts which you post, and your friends whom usually or less visit you, and the frequency you log in Facebook. Moreover, it presents you a sort of character profile depending on their activity. It can label your Facebook friends as pawns, stalkers, Liabilities, obsession and scapegoats. I think it is the most powerful software which coded by professional data miners. It reminds us that Facebook knows everything about you. We should always pay attention to our privacy setting on Facebook. The Digital Shadow tool can help us see your own detailed breakdown, then change our privacy settings in time.