Shattered Galaxy gives players the ability to alter their world map, but the changes are ephemeral and unimportant.
 

EVE Online

EVE Online Isk (official site) also lets players alter the game world, but in much more powerful, meaningful, and often painful ways. EVE Online’s single server spans a galaxy of thousands of solar systems. The center of the galaxy, when new players start out, is a relatively static and safe place. NPC police ships will warp in to attack players who fire on other players. NPC agents at various space stations will offer a limited number of quests, which will eventually start repeating themselves.

On the galactic rim, the game is completely different. There are no NPCs or pre-defined factions. Solar systems are owned by alliances of corporations (a corporation is essentially a guild). Players run their own economies, mobilize their own war machines, and plot their own political intrigue. Weapons platforms and jumpgates built by players need supplies to keep operating, and these supplies must be mined by players and transported by players in armed convoys, lest enemies waylay and destroy them. When a corporation loses a solar system to another, any assets its members have stored in the local space stations are trapped there. Players themselves may be trapped as well, logging on after a lengthy absence to find themselves on a space station in a system full of hostile ships. Although they cannot be attacked while on a station, launching a ship would invite a swift death. EVE Isk gives its players great freedom to shape the galactic rim into whatever they wish, which turns out to be a Balkanized version of the Wild West, full of shifting alliances and danger. Despite all the control available, the lack of safeguards keeps some players away.