Minecraft - Possible Social Concept

1. A social freemium concept of the game.
2. Resources can be obtain through premium purchase.
3. Each player has a small world, owned, for building a home shelter, farms and trees
4. Player are able to co-op in caves run (different world) for rare resources.
5. Player are able to co-op in nether world run (different world) for rare resources.
6. Player are able to visit friend's world but cannot mine or take anything.
7. Player world can be expanded through achievement or use level points to exchange.
8. Player are able to co-op in various popular mod maps, these mod maps can be unlock with premium purchase.
9. Player are able to craft custom character skin. Some characters skin can be purchased as premium.
10. Player are able to adopt pets. Some pets can have different color or different skin as premium purchase.

With over 28 million registered users.
5 million of them purchased the game.
Social game concept on Facebook.
Freemium and Premium concept.

Quite a feasible business for a game.