BioShock and its upcoming sequel are both set within the underwater dystopia of Rapture. BioShock 2 developer 2K Marin doesn't think the potential of the setting is fully tapped yet, though.

"I think Rapture remains fertile for as much expansion as a team sees in it," 2K Marin creative director Jordan Thomas told OXM. "I absolutely believe that there might be future games set in Rapture in whatever time period, but I would also say that I think that the BioShock brand is big enough that it could evolve."

Added Thomas: "Currently, we find Rapture fascinating, that a city that large begs further exploration, a city with that much history, but I can't speak to specific sequels past BioShock 2 now, but I could speculate and say merely that the type of experience that type of experience BioShock is is flexible enough to see lots of expansion down the road, and a lot of different directions. Whatever it is, it has to surprise the player."

No doubt plenty of people, upon viewing screenshots of the first BioShock, assumed that wandering around a dingy underwater city would get old quickly but the developers managed to imbue the setting with a surprising amount of variety (caves, a forest, a furnace, etc). So much thought was put into Rapture, its look and its history that it would be more shocking if they didn't set another game there.