If you are trying to create an MMORPG you might want to look at this.
[url]Questions for this game engine!! - #2 by 4ian]
I’ll bet there is someway to create a login system. If there is a server that saves there progress and character then loads it into the game in some sort of complex way. But if you plan on 100+ online players walking around in a 3D world. You might want to see the post above.