LIBERTY CITY, New York - Two of the biggest franchises in video games are looking at sequels that they hope will revolutionize the genre. Rockstar's Grand Theft Auto IV allows players to move about freely in a living city - and, if they choose, destroy it with automatic weapons fire. Polyphony's Gran Turismo 5 takes hyper-realistic graphics and puts the player in the driver seat of hundreds of enticing cars, which they can try out on the virtual versions of exotic racetracks from around the world.