1. Extensive Knowledge
Know all the details about them, personality to significant moments, and know any obscure facts only a fan would know (ignore the fact this game lasts a couple hours or so)
2. Creative Output (optional)
Fanart or talking about them
3. Consistent Engagement
Cause replaying the game is obviously necessary :p
4. Emotional Investment
Do you really love them? Are they you?
5. Merchandise
Get all the clothing and mugs from the nonexistent shop.
6. Time and Effort
replay it more
7. Social Proof
talk with more people
8. Personal Projects (optional)
Cosplay
9. Analytical Engagement
Write essays
10. Role-Playing and Immersion (also optional)
Roleplay