the expantion pack contains exclusive areas including the classic liberty city and some parts of san andreas it has the same game engine as gta4 exept you can fly planes, sky dive (parachute) and you can also fly to other parts of the world (san andreas). the classic liberty city is added on to the the new liberty city. when i left, the guys were thinking about not putting it on to xbox 360 because it got lost and damned and the ballad of gay tony, whereas ps3 didn't