@suricrasia when I was a kid there was this webpage thing that, in my MIND, I remember being called "the neverending story. You would read a page then you could submit a page that branches off, and that could continue on recursively.
Of course I don't remember the web address or anything, so I can't even Wayback Machine it.
I guess I could reimplement it pretty easily myself, though.
@suricrasia and, as others have mentioned, MUDs - I've only started playing one, but the world's history is affected by players, interacting with the admins-as-NPCs or deities, building things together.
Most recently, in Achaea, players and some of the Gods worked together to make a "Spire of Time", a time capsule for players to put memories into, to be retrieved in hundreds of game years from now.