The classic first-person shooter BioShock is a Mature-rated game for players 17 and older. So why did movie studios feel that the proposed film adaptation should have been PG-13?

According to Pirates of the Caribbean director Gore Verbinski, who was attached to the BioShock movie before jumping ship two years ago, no Hollywood backers wanted to keep the movie aimed at adults.

“I just wanted to really, really make it a movie where, four days later, you’re still shivering and going, ‘Jesus Christ!,’” Verbinski said to ComingSoon.net over the weekend. Since he couldn’t find a studio that would fund an R-rated version of BioShock the project never gained much steam, he said.

“I wasn’t really interested in pursuing a PG-13 version,” he told the website. “Because the R rating is inherent. Little Sisters and injections and the whole thing.”

BioShock creator Ken Levine said last year that the movie is still an “active thing,” but without an attached director or producer, it seems to be stuck in the purgatory that filmmakers refer to as “development hell.”

The next game in the series, BioShock Infinite, will ship in 2012 for PlayStation 3, PC and Xbox 360.