Replay value

Replay value or replayability is a term used to assess a video game's potential for continued play value after its first completion.

Factors:

1. Plot

2. Multiple classes

3. Multiple characters

4. Alternate paths

5. Performance grading

6. Unlockable characters and content

7. Alternate endings.

8. Games where the map and starting position is different every time you play it.

9. The community-developed mods.

10. Multiplayer is also often considered to increase the lifespan of a game.

11. Some games encourage replaying missions by adding Time Trial and Time Attack modes.

12. Secondary objective that may be difficult to complete, but necessary for additional elements to be unlocked.

13. New Game+ mode which lets players replay the entire game using select items or abilities from their first play through.

From: https://en.wikipedia.org/wiki/Replay_value