BioShock could have made a wonderful movie. But realistically it would never been a wonderful movie, even if plans for a Gore Verbinski-helmed adaptation of the Irrational's opus hadn't been abandoned. It could only have been an overload of CGI that sacrificed depth and tone for a visual onslaught. I'm sure of that, and I'm glad the movie didn't happen. But the real reason it didn't is that backers Universal were spooked by the commercial limpness of the Watchmen adaptation, taking it as a sign that there wasn't enough of an audience for an R-rated sci-fi movie at the kind of budget Verbsinki demanded; he then wouldn't agree to a much a lower one. A later attempt at a cheaper movie by 28 Weeks Later director Juan Carlos Fresnadillo was nixed by Ken Levine, who told Eurogamer that "I didn't really see the match there."
The movie did at least make it to concept art stage, a few examples of which have recently emerged, and depict new areas of Rapture planned for the big screen.
The images by concept artist Jim Martin (whose portfolio also includes assorted Matrix, Pirates of the Caribbean, Riddick and Star Trek instalments) shows both familiar and novel views of Andrew Ryan's doomed attempt at an undersea utopia, and broadly speaking suggests a more imposing and sombre take on Rapture.
Whether any of this would ever have been made cinematic flesh is unknown, but glimpses of the construction work and foundations beneath the city are fascinating to see, as are hints of a more inhabited city. The shot atop this post implies an increased focus on horror too, plus more of a look on how Big Daddies are made and maintained.
There's much more on Martin's site - no big reveals, but certainly a sad sense of what might have been.