SecondLife does this. You have to use a real name, address and credit card to register an account. But in-world, no one knows who you are and there is no pract

SecondLife does this. You have to use a real name, address and credit card to register an account. But in-world, no one knows who you are and there is no practical way for anyone to find your real identity. And for misbehavior (griefing or harassment), they can block you (by IP I guess) for days, weeks, or forever.