Multiplayer game mechanics

1. Player Achievement vs Player Advancement (Gamification Player Progression Tips)
2. Player Participation vs Player Contribution (Gamification Achievement Systems Tips)
3. Single-Player Achievements vs Multiplayer Achievements (Gamification Achievement Systems Tips)
4. Game Client vs Game Server (Player-Centric Gamification Tips)
5. Player Engagement vs Player Retention (Player-Centric Gamification Tips)
6. Player Motivation vs Player Engagement (Gamification Player Progression Tips)