Thousands of videogame shops opened the instant Tuesday arrived for expected hordes of "Bioshock" fans eager to return to the grim, morally-tattered undersea world of Rapture.

The "shocking" sequel to the title crowned 2007 Game of the Year launches globally after its release date was delayed several months in hopes of an improved economy and videogame consoles being popular holiday season gifts.

"Bioshock" is the brainchild of Ken Levine, who told AFP that inspirations for the game's dystopic storyline came from many places, including the films "Citizen Kane" and "The Fight Club" and the work of author Ayn Rand.

The game has been lauded for its play and disturbing moral choices.

Key characters in Bioshock include girls with hypodermic needles for arms and "Big Daddy" brutes for bodyguards.

"One of the most exciting aspects of the original 'BioShock' was how fans responded with adoration for the game, from creating homemade Big Daddy suits to their own BioShock-inspired art and videos," said 2K president Christoph Hartmann.

"We felt it was only fitting to reach out to those passionate fans with nationwide Return to Rapture midnight openings."

More than 2,500 GameStop and Best Buy stores will be open when clocks strike midnight to begin selling copies of "BioShock 2."

The sequel was a collaborative effort of California, Australia and China studios of 2K, a publishing label of Take-Two Interactive Software based in New York City.

The first-person shooter game is set approximately 10 years after the events of the original "BioShock," according to 2K.

Players enter a fictional scene in which a monster has been snatching little girls and bringing them back to the undersea city of Rapture.