GTA 4 the concept of the game

Although Liberty City may not differ greatly from Niko's homeland, being different and standing out is definitely a major theme with Grand Theft Auto IV. While GTA VICE CITY and GTA San Andreas were considered to be part of the GTA III trilogy (same graphics engine, similar characters, similar mission style, etc.), Grand Theft Auto IV is considered a fresh start for the GTA series, focusing more heavily on realism and storytelling than in previous titles. This is why it's been dubbed GTA4 and not GTA6 (as many had originally anticipated), even though it's the sixth major title in the series.