What if you created a new world, you spawn in all alone, you build your house, and then "[SERVER]: someone has appeared" and a npc that has a certain skill or job due to how the house is. Like if the house has a furnace it can cook, and ect., so then you have a reason to build houses, for people that will actually show up, and you could have a currency, economy, have good vs. evil (like robbers/griefers). I think it would enhance the gameplay, and provide a new goal for the minecraft game, slightly like terraria, but in its own minecraft-ish way.... This would allow the people that like civilization games to do that, and now have to go get plugins that are overly complicated, or going through the stages o adding a mod. This would be very complex, but it would be cool if it was a game mode like survival and creative. It could open up new possibilities, bring back old fans that have gotten bored with the same concept and were more of a strategy or civil person, and bring in a whole new gaming group. I think it can be done, it will take time yes, but it would be very interesting, and new. i think that is the main saddening part of minecraft, there isn't a point to build more than one house, other than a farm maybe and a mine, but if you can build towns, cities, kingdoms, or even castles, it would give the creative group of minecraft a reason to build.