"I can pretty much guarantee to you that if BioShock wasn't successful, there never would have been another game like this," Levine told us in an exclusive interview. "I don't even know how we convinced people to pay for BioShock. These games had never made any money - everybody told us when we were pitching BioShock, sounds like a great idea, you'll sell 150,000 units - next!"

Levine was responding to a question about the player response to BioShock - in particular, the criticism from some players that the game was less complex or challenging than they'd hoped. He doesn't agree with that assertion, and thinks hardcore fans of the genre should focus on the positives.

"Honestly, really deep down, we wanted to popularise this kind of gameplay that we've been attached to for so long," he explained. "If the first iteration of it was a tiny bit simpler than System Shock 2... Look, how many of these type of games do you think are going to be made now, compared to how many were going to be made before? It took us how many years to get this game green-lit?"