Clear rules and guidelines

1. Free-to-Play vs Pay-to-Play (Player-Centric Gamification Tips)
2. Individual Progress vs Team Progress (Gamification Player Progression Tips)
3. Player Expectations vs Player Satisfaction (Gamification Achievement Systems Tips)
4. Social Gaming vs Competitive Gaming (Gamification Achievement Systems Tips)
5. User Generated Content vs Developer Generated Content (Player-Centric Gamification Tips)