The only thing that felt halfway similar to me was Infamous. As far as being able to climb on junk and fly around kinda. It wasn't the same, but it was at least reminiscent. I think if I was going to go back to messing around in a virtual city, though, I'd go back to my ongoing game of Saints Row III. I never played the others, but that game is just so much ridiculous fun, even if the story is basically meaningless to me.