It is my understanding that muds (and all the flavors of Mush in particular) can sort-of do it, by letting players create their own story through roleplay, supp

It is my understanding that muds (and all the flavors of Mush in particular) can sort-of do it, by letting players create their own story through roleplay, supported by an extremely open (and often player-modifiable) world, as well as good admins / GMs. That is more like "computer tabletop", however, and doesn't scale beyond a small number of players.