Storyline

The protagonist and main character (controlled by the player) is a super-athletic remix of 50 Cent named Nicolas Cage or "Nick" for short, who is on a mission to become the criminal mastermind of Lunar City. (a ficticious location on the Moon) Nick starts out with no money and weapons and must gain Gil and experience points to level up from Wanna-be Juvinile Delinquent to Pimpin'-in-da-'hood Master.

Major differences from Grand Theft Auto

In Grand Theft Cosmo, the police are replaced by Men in Black and police cars are replaced by black helicopters which are actually interplanetary police craft, or IPCs, used by the Men in Black to fight interplanetary crime within our own Solar System. These are just as stealable as any other spacecraft. In the Grand Theft Cosmo universe, interstellar and intergalactic crime is handled by the PIGS - a more advanced race than humans who usually only appear in the game when the player's Wanted level has reached the maximum.

In a short bonus video in the Grand Theft Cosmo Special Edition entitled "Ultimate Awesomeness" that parodies Star Trek and The Matrix, the character named CATS theorizes that interdimensional crime is policed by a race even more advanced than the PIGS, called the "United Nations".