IGN PC has published a large six-page interview with Irrational Games' Ken Levine, in which the creative director reveals quite a bit of new information about their upcoming sci-fi RPG, Bioshock. Here's a bit about the game's linearity:
Q: At this point in the history of videogames, we've experienced both linear and open design games. They both have their strengths and weaknesses. What are you going after in BioShock? Are you going to create some linear sections and some open sections?
A: It's probably much like System Shock 2, in the sense that the world is open and you can go back and forth between the entire game. There are no levels, per say. I mean, there are some loads as you go from one area to the next, but you can freely go back and forth in the game as you progress. Our goal has always been a little different than say, a Deus Ex game, where you can follow this geometric path or that geometric path, in terms of that hallway, that hallway or that hallway. It's more like this: We give the player a broad set of tools and we say, "How do you want to handle this problem?" "How are you going to approach this problem set in the game?" It's a huge amount of choice. And we have invested a huge amount of time and research into our AI.
We built what we call an AI ecology. AIs have goals of their own. First, we have several classes of AI. There are the Aggressors who were the foot soldiers of Rapture during the conflict. They behave pretty much like monsters that you're accustomed to seeing in games. They're very aggressive toward you. But there are also two other classes of AIs in the world called Protectors and Gatherers -- this big guy and this little girl. And the Gatherer's role in the world is to go around collecting this resource, "Adam," which is what drives all these genetic changes from bodies left over from the war. They sort of recycle that material and are able to recycle that biologically, in their own body, and they're guarded by these big protectors, these big lugs you see in these diving suit get-ups. And they won't bother you if you don't bother them. They are carrying around a lot of resources around that you might need. So the aggressors are interested in them, and there is often conflict between the Aggressors and them, and you're potentially interested in them. But if you don't bother them, you just observe them going through their behaviors; they have a relationship with each other. They're a team.
When she climbs out of these vents in the hallway, she wriggles her way out of this vent, and hops down on his shoulder, and he helps her to the ground. Then she runs ahead and yells "C'mon, c'mon!" and he sort of tries to keep up with her, and he grumbles when she gets too far ahead. We spent a lot of time building up this whole relationship and making a believable relationship between them. Almost like a fraternal relationship. This is something we really wanted to do, to give a sense of these characters having a real existence in this world. And, we also have a security system that has these bots and security cameras. And you have a whole range of tools that you have to interact with these guys. They range from, obviously, just fighting them to turning one against the other. Or you can use a plasmid, which is our genetic power-up to make these Protectors think that you're one of the Gatherers, and they'll follow you and protect you for a period of time. So you can turn the security system against the Protectors, we call this tool the "Gatherer Cry," and they imprint upon you. So, the first thing you have to do is that you have to observe the relationships in the world, and then you can engage and take advantage of those relationships.