So I'm going to leave it to you what makes your site interesting, but I will require that you have users/creatures/anthropomorphic entities, friendships/relationships/adversaries, some sort of role-based access between these entities, also messaging/chatting/logging of data would be nice. Use a no-sql database. Use your creativity and create as many interesting features as you see fit.
FIRST DEADLINE: July 14th at midnight I want a conceptual map.
REAL DEADLINE: July 21st at midnight a working backend and personal growth report.