Utterly Mad

If this hasn't died yet then in the experience I've had in the game development world, I'd suggest that this project is far too ambitious for even a group of people with little to no experience, even if one or two of you had some experience it would still be difficult.
However not impossible. Start small, I mean really small, you're not gonna start by making the game you want, you're gonna start by barely making a crappy Mario clone, but it'll give you that valuable experience, slowly work up to this kind of project and eventually you'll make something absolutely magnificent.
Also I'd like to point out, if you're going in a multiplayer direction with this it'll likely be impossible for you to do without professional education on game development, a lot of experience and the money to rent, or own, a server.

But all in all, good luck with this, I hope the project carries on and one day does well for itself.