To further this distinction, Guilds are bound to territory within the game. With enough power and resources, a hierarchy of guilds can conquer a city-state to use as a home base, an open marketplace, a military outpost or a mercenary stronghold. As more city-states are taken, the guild becomes a Kingdom. Still more will fashion a Kingdom into an Empire. Guilds may declare War, leading to an entirely new type of game play.
Rules of engagement can arise, and intrigue and diplomacy become a valuable commodity.
Mercenary armies can be formed, moving between guilds to appeal to the highest bidder. Guilds can set their own recruiting policies, and players can be promoted up through the organization over time. No, not all of the Cities will be player owned. Many of them will be run by the Game Administrators. City-states will remain in short supply by design.