Player engagement metrics

1. Tradable vs Sellable (Virtual Economy Gamification Tips)
2. Free-to-Play vs Pay-to-Play (Player-Centric Gamification Tips)
3. Player Data vs Game Data (Gamification Achievement Systems Tips)
4. Player Progression vs Player Ranking (Player-Centric Gamification Tips)
5. Item Rarity vs Item Value (Virtual Economy Gamification Tips)
6. Player Path vs Player Journey (Gamification Player Progression Tips)
7. Economic Trends vs Game Trends (Virtual Economy Gamification Tips)
8. Game Unlockables vs Game Achievements (Gamification Achievement Systems Tips)
9. Player Skills vs Player Competencies (Gamification Player Progression Tips)
10. Endowed Progress Vs. Loss Aversion in Gamification (Compared)