When people have some extra time, they often play games on their smartphones. Most apps urge connecting the game to social networks to bring in friends for example. But the German web-safety initiative Schau Hin warns people against this, because the app gains access to the user's personal information and lists of friends.
Information about the game along with other advertising messages is passed along in your name, and your friends are likely to be puzzled and annoyed by getting such messages.