You should check out MUDs - MUDs (being entirely text based) are easy for any old person to modify and create within... no texture or graphics work - just writing. As a result a lot of MUDs have extremely dynamic worlds that have large ongoing plots being managed by the GMs.

The old Ultima Online had GMs pop in and create quests and random events. Non-scalable, but - oh - so much fun

"Non-scalable" is a rather medium excuse though. There's quite a few ways around this:

1. Raise prices enough to employ enough humans. I imagine there's quite a few people out there who'd be happy to spend a pint's price on a quality gaming experience.

2. Give the GM better tools. Higher level half-scripted events + better sentiment monitoring. I imagine a single competent GM can run in parallel a bunch of events keeping quite a few players engaged.

3. Recruit experienced players to do this job for you. I imagine there's quite a few people who'd do this job for in-game goods, as long as an hour of GM-ing gives a couple hours worth of grind of goods.

Currently building this. We're launching in August.

Give us some kind of link / mailing list so I dont have to remember 'til august. Spoiler: I wont remember.

Seconding maerF0x0, what's the game called?

Gemstone IV does this.