1. A series of tasks that are easy to learn but difficult to master.
2. An elaborate and exciting storyline.
3. Characters with whom players can empathize.
4. The ability to create personalized avatars for game characters.
5. The manipulation of time during game play (for example, changing from day to night or dark to light).
6. Carefully designed relationships between game characters.
7. Random games of chance mixed into the overall game play (such as the opportunity to win a new feature).
8. A constant and regular series of rewards (for example, you earn a new badge or feature after you play for a certain amount of time).
9. Opportunities to interact socially with others through the game.
10. Repetitive tasks that have no defined endpoint.