15 years ago, GTA IV upended my relationship with New York City by providing me with one. Before I knew the sights and sounds of my own home, I knew Liberty City like the back of my hand.

Grand Theft Auto 4 sales topped half a billion dollars during its first week of release, earning about 5 times as much as the blockbuster movie, Iron Man. GTA 4 takes place in Liberty City, a parallel ...