Elsewhere there has been plenty of discussion of the impact of the game world via player or guild housing. Cool as the basic idea is, there are severe downsides due to players not always being logged in, clutter, and inactive players leaving behind abandoned structures, and so on.
Consider though if the world impact wasn't by a direct mechanism owned by players, but instead via communities which the players align themselves to, in a subtler sense of the word "ownership".
They could swear allegiance to some minor lord, do his bidding, and see that community slowly grow from their efforts and contributions. The central village might grow in size and capability, outposts may be established, which in turn grow, until eventually a mighty empire straddles the land.
As their reputation with that community builds they might even be afforded some input into governance, perhaps some voting rights, or able to petition the ruling council for more of a particular kind of activity vs another (more mining vs farming, or colony expansion, or raiding, or alliances).
In my mind this design has various advantages:
- the world can grow and change but in a manner not easily exploited by players (no rude words spelled out by the judicious placement of buildings, for example),
- although players invest a sense of ownership into these communities they don't truly own them, and thus have a small buffer against direct griefing,
- if the community the player has aligned themselves to is suffering horribly whether due to griefers or simply other larger/more organised communities, then the player can switch allegience and move on,
- since property isn't directly tied to individual players, when those players go inactive or awol it doesn't really matter .. there will be other players who will come along and pick up the slack,
- those players that build up influential reputation with that community don't get a lock on controlling that community .. whilst they might have more influence in decisions made, their participation isn't required for decisions to be made (compare this to guilds whose guild leader has gone awol, making it impossible to change various guild settings).
Tobold also wonders about impact PvP and the resulting discussion is interesting.
Update: found someone else with very similar ideas. I disagree that regular resets of the game are needed though - certainly there is the problem of positive feedback loops resulting in some faction or other dominating. What is needed there though is not some artificial game reset mechanism, but countervailing forces designed into the game. History is full of examples we can draw on - once empires get large, bad things start to happen. They succumb to internal bickering and sub-factions splinter off, they get fat and lazy and whomped by lean and mean barbarians, the oppressed minority factions draw from deep within to find a hero and spark a rebellion. Design in some dynamics that kick in at the extreme ends of the equilibrium which can result in the tables being turned, and things will get interesting.