For me, it seems a daddy's boy or girl, would be someone who is looking to be led into life no matter what their true age is.  Told what to do, when to do it, and to be taught how to do it.  Every sub looks to it's daddy to control it's life and to lay down the rules it must follow.  Discipline must naturally follow.  It is up to the daddy to learn the sub's strengths, weaknesses, and personality, and determine it's path in life.  A boy or girl who needs a daddy can be assumed to be destined to be a servant, a submissive, or a slave, and it is up to daddy to prepare it for that life.  I can't think how to do this as a game or with less than tpe, but I do know it can be started online so long as everyone is honest and the daddy/sub relationship is real.