GTA IV reimagined Liberty City for the RAGE engine generation. Denser, grittier, more grown-up than GTA 3's version. The map that started the modern Rockstar tradition.

What changed from GTA 3

RAGE engine - new physics, new lighting, new pedestrian density. Reimagined boroughs - Algonquin (Manhattan), Broker (Brooklyn), Bohan (Bronx), Dukes (Queens), Alderney (New Jersey).

Smaller geographic footprint than GTA SA but much denser - the trend that GTA V and GTA 6 continue.