I'm familiar with SL. And yes it has some of the elements of this, what it doesn't have (or didn't when I last looked at it) were constrained physics story line

I'm familiar with SL. And yes it has some of the elements of this, what it doesn't have (or didn't when I last looked at it) were constrained physics story lines and a questing model tied to in game currency. Mostly it was around converting "real" money to "Linden" Dollars[1] to facilitate in-game transactions. [1] And at the time (2008) there were sites that would convert your Linden dollars back into cash.