Developers collect data on who was playing, for how long, how well, and how much money they were spending. It doesn’t seem like sensitive information, and it’s useful mostly because it helps developers target their Facebook ads to find more people who will “monetize well” on these games. It’s a characteristic they’re incentivized to consider flatly, extracted from any ethical considerations of whether that sort of person ought to be marketed to. For instance, if the person spending hours playing a game where you fling upset cartoon birds was, in fact, a child, or someone who struggles with gambling addiction or impulse control, or is otherwise vulnerable. Facebook finds Angry Birds a new user and collects its check. Angry Birds finds users that will spend enough money to offset the cost of being found. It’s a good deal all around.