Non-linear gameplay

1. Gameplay vs Game Plot (Player-Centric Gamification Tips)
2. Game Unlockables vs Game Achievements (Gamification Achievement Systems Tips)
3. Leveling Up vs Ranking Up (Gamification Player Progression Tips)
4. Open World vs Closed World (Player-Centric Gamification Tips)
5. Player Participation vs Player Contribution (Gamification Achievement Systems Tips)
6. Skill Progression vs Ability Progression (Gamification Player Progression Tips)