GTA3 was actually released roughly at the same time and probably overshadowed Mafia. I think Mafia was the better game overall, though.

Wasn't Vice City was the Grand Theft Auto of 2002/03? ;)

More to the original point, the first GTA remains along with Age of Empires one of my all-time favourite games. It's easy to forget in light of the franchise it became what a novel and crazy little game that was.

What I find absolutely fascinating is that there are only 16 years between the release of GTA1 and GTA5. How could such amazing progress have occurred in such a short timeframe? It's unbelievable.