I think that's harder. Making MMORPG's on your own, or even with a team, really isn't easy, trust me. It'sh ard enough making a single-player RPG, even with my 5 years of experience with gamemaker. More powerful programs often also mean more difficulty making difficult games. Sorry to dissapoint, but I don't think you'll find something finished and of good quality like that. It's possible, I know a master of Gamestudio for example, could easily make that, but... hmm, I really don't know. It seems too complex or too hard to make.

I know many users of gamemaker have tried making MMORPG's, but so rarely do they get finished and even more rarely (or in fact, never) you can switch jobs or something alike. Still, out there somewhere, there might be a game like that. I don't know, I don't really keep track of all the free-made games out there. It's hard enough making my own while doing my other daily stuff. Sorry to not be able to help.