This is the official game description which is from the official Grand Theft Auto IV website (www.rockstargames.com/iv)
What does the American Dream mean today?
For Niko Bellic, fresh off the boat from Europe, it is the hope he can escape his past.
For his cousin, Roman, it is the vision that together they can find fortune in Liberty City, gateway to the land of opportunity.
As they slip into debt and are dragged into a criminal underworld by a series of shysters, thieves and sociopaths, they discover that the reality is very different from the dream in a city that worships money and status, and is heaven for those who have them and a living nightmare for those who don't.
Developed by Rockstar North, Grand Theft Auto IV will be simultaneously available for Xbox 360® video game and entertainment system and PLAYSTATION®3 computer entertainment system and will be in stores worldwide on April 29, 2008.
From elelamb :D