This week's announcement confirming a movie treatment of last year's hit shooter BioShock has, once again, raised the hopes of gamers that their hobby might finally get a film adaptation as compelling as the source material. After all, BioShock has strong visuals, good writing and a story with a twist. But director Gore Verbinski will have a lot of challenges, challenges that underline the difficulties in the game-to-movie transition.

Rapture Is the Star

Verbinski's experience on the spectacle-filled Pirates of the Caribbean movies should come in handy here, because the real draw of BioShock is the underwater city that has fallen apart. The more that the director and screenwriter focus on Rapture, however, the more likely it is that there will be major deviations from the game's plot and message. BioShock could become a modern-day Atlantis story, more about how the great city sowed the seeds of its own destruction.

Though the player controls the action, the story of BioShock is about ambition and hubris, how single-minded adherence to individualistic pursuit of excellence brought down an entire city. The decaying buildings, the haunting period music, the dark corners and the blinking lights ? everything is a reminder of a dream that has died.

So, there will be a strong desire to add a before to the after, to spend a lot of time on backstory about the Rapture that was. In fact, you could make the movie about the collapse of the Ryan dream and not about one guy running around killing in a city gone mad. This, however, is not the story of BioShock.

If you spend a half hour or so on the founding of the city and flash forward to the opening plane crash, then you lose the sense of discovery that powers the game narrative. Could you change the story from one of discovering the mysteries of Rapture to the rediscovery of a lost city? Can you turn the protagonist into a journalist trying to find out what happened to the Shining City on a Seabed?

And while we're on the subject?

Who Are the Characters?

BioShock as a game has one actor for most of the story. A single survivor of a plane crash is given missions and advice from a mysterious interlocutor. You control a guy with guns and lightning bolts getting instructions over a radio. The explanation of what he is seeing comes entirely through recorded diary entries and the occasional really big enemy to kill. There are no sane one-on-one encounters until the big turning point.

Can you establish the cast of BioShock and still keep it as a game about shooting things and setting them on fire without increasing the number of people doing the gunplay and arson? This would take it down the path of the Doom movie, which was not about one super-marine, but a squad of them. BioShock, though, has a moment that is, essentially, about individual choice. Will that be as powerful if you have an entire planeload of people running around Rapture?

Then you have the iconic figures of the game -- Little Sisters and Big Daddies. The choice of whether or not to harvest ADAM from the Little Sisters can only really handled in film by a dialogue. Internal soliloquies don't work quite as well, I fear, but that means adding a second person at least. In the game, Big Daddies are a constant fear, but can't simply become a movie monster and maintain their mythological power. You only have two hours in a movie (or maybe three if the last two bloated Pirates of the Caribbean movies are any indication) so you have to decide when and why you deploy your Little Sisters and Big Daddies. The protective relationship between the two is central to its creepiness, but it wouldn't take much for a screenwriter to warp that into an exploitative relationship that adds further motivation for the protagonist.

Because the setting doesn't necessarily have to be all about turning corners and killing things, there is also a greater likelihood of introducing a romantic subplot. Not everyone in Rapture needs to submit to the madness, after all.

What Is the Moral?

Game critics have made a lot of BioShock's critique of Objectivism, science and free will. It sets the scene with the bathysphere slideshow about how Rapture frees you to pursue your talents as far as they will take you without any of that messy religion or politics or state control. Society is for suckers. The lesson is slowly unveiled, culminating in a confrontation that calls into the question the very nature of individuality and choice. The divide between freedom and slavery is as simple as the ability to choose.

If you had read no commentary about the game at all, it would be entirely possible to play through it and not plumb the depths of the commentary that Ken Levine and 2K Boston were making. BioShock can be seen as yet another pretty first-person shooter with some really neat mechanics.

Traditionally, films have been better than games at imparting moral lessons or driving home philosophical points, but Verbinski and the screenwriter will have to decide first whether the game's message is the one they wish to make, or if they even want a message at all. Ryan is a sort of Frankenstein, only the city is his monster; "BioShock" the movie could choose to keep it simple by focusing on his ambition and arrogance instead of making any larger point about free will and social constraint.

No matter how you slice it, BioShock will require some major adaptation in order to work on-screen, much more than Halo or Prince of Persia will. And these adaptations will worry many of the thousands of people who loved the game. A lot of it will come down to whether or not BioShock is seen as a setting, as a parable or as an adventure.

How Do You Deal With Plasmids?

Where the "Prince of Persia" movie can just have the hero running around and making acrobatic moves, BioShock's central mechanic involves mutation into superhero status. As fantastical as the idea of an underwater metropolis is, once you add a hand that fires bees at enemies, you are well past plausibility even in a world that is sideways to our reality.

Gamers are used to this sort of nonsense, of course. You jam your arm with magic sauce and the next thing you know you are Bee Man. In the context of the game, it works as myth -- humans transcending human nature and becoming monsters as much as gods.

If it were magic, it might work better for a mass movie audience than science-y arm goo would, but a 1950s-1960s setting doesn't lend itself to the same fantasy elements that a far future or distant past setting do. Plus you have the imagery of gaining superpowers by injecting drugs.

Verbinski, of course, turned a Disney theme park ride into a billion-dollar franchise, and partially through the expansion of magical elements to go along with the period swashbuckling and legends of the Lost Dutchman. And there are mystical elements in the Indiana Jones series, though more as deus ex machinas or MacGuffins than as central plot mechanics. You really can't have BioShock without the science run amok, so plasmids will need to be there somehow.

Tentatively scheduled for 2010, there's still a good year or so before a lot of this stuff gets finalized. Verbinski is, reportedly, a serious gamer, so he'll want to work with a script that is both true to Levine's vision and would work well on-screen. The direction that the production team takes will have long-reaching consequences for casting and the like.