"What is the possibility of creating a game/map slightly modified into a MMORPG.  With infinite maps and crafting in now, there would only be a couple things to modify.  You would have to adopt some system of promotions in-game, as well as locking all abilities of a normal character, to be unlocked through promotion.  Probably, you would also have to create skins for everyone, which change on promotion.  
The game could actually be governed by players themselves, with minimum supervision from ops (easily explained in-game as magicians, etc.)  But a council system of 10 people, with the 9 heads of different jobs, and one leader with 2 votes, could govern one city-state fairly well.  With an initial beginning as two warring city-states, the game could expand to a large political world.
Deaths in-game would result in demotion one or two levels, depending on situation.
Probable 9 classes:
Warrior: outfitted with weapons, sent into battles, which could be scheduled, and raids, which can be random.  An ax to destroy wood could be given, but they would be unable to get through any other materials.  Higher levels would supervise in-battle promotions for work done.
Archer: I think this one is self-explanatory.  With promotions, would be in charge of other archers, same as warriors.
Explorer: given some bad equipment, they'd be able to multitask.  Later ones would be sent as diplomats to new cities.
Hunter: They would use bows and swords, and would be in charge of hunting monsters for resources.
Farmer: This one's obvious.  Low-level ones would have small farm, superiors would supervise.
Clerk: In charge of regulating in and inter-city trade.  Rise from merchant level to supervisory.
Miner: In addition to the obvious, might also share the ability to log forests with the farmer.  As promoted, superior tools, and supervision of mining projects.
Builder: Would be able to place and sometimes destroy blocks.  Once promoted, would become architect, planning buildings.
Crafter: Able to craft materials.  As promotions improve, would get ability to use superior materials.
Leader: Manages council of a city.  Upon death or resignation, council would elect one among themselves.
City-states should have mostly barren outlying territories, which can be fought over in wars.  Wars should be composed of both people with fighting classes, and AI's, who will be hirable as guards and soldiers, and whose numbers will correspond to gold invested by the city-state.  Trade, incidentally, will be regulated by clerks, and will balance the resources of a city-state.
Tell me if you have any comments/suggestions.