Free copies of the game "Grand Theft Auto 4" are not legally available. It is a commercial product that must be purchased from a retailer; downloading the game for free is copyright infringement.
Rockstar Games, the developer of "Grand Theft Auto 4," offers a list of authorized retailers on its website. The game can be purchased and downloaded from any of these retailers, but is not free. Downloadable content for the game also requires a purchase, and cannot be obtained at no cost. These episodes are available as downloadable additions to "Grand Theft Auto 4" or as a standalone game package on a physical disc.