I don't know.
I do know that as I play the only MMO that I play that I constantly think of (solving the problem of) how it is designed, and what it would take to (re-)implement it on my platform of choice... HeroEngine.
That would be Final Fantasy: XI (Online).
It's game mechanics and world design at both macro and micro-levels is remarkably dense. And totally do-able (if you ask me) on Hero.
--A
