It's a rare and beautiful thing indeed. NetHack is the other obvious comparison, but my impression is that development has happened in bursts of activity rather

It's a rare and beautiful thing indeed. NetHack is the other obvious comparison, but my impression is that development has happened in bursts of activity rather than as a continuous effort. Some MUDs have this kind of longitudinal development - like the Discworld MUD or LambdaMOO. And of course the AAA commercial MMORPGs with huge budgets and cattle users that get milked $14.99/month. Though I suspect those are unsustainable in the long run.