Challenge modes

1. Game Characters vs Game Avatars (Gamification Achievement Systems Tips)
2. Game Unlockables vs Game Achievements (Gamification Achievement Systems Tips)
3. Power-Ups vs Boosters (Player-Centric Gamification Tips)
4. Skill Progression vs Ability Progression (Gamification Player Progression Tips)
5. Game Narrative vs Game Mechanics (Player-Centric Gamification Tips)