"The Xbox version, because it's in contemporaneous development with the PC. When it was started, basically was conceived as a console implementation of what we're trying to do on the PC, as opposed to a port where they take whatever we do on the PC and "boom" slap it on the Xbox. The Xbox version was designed from the ground up to support co-operative play over System Link and Xbox Live. There [were] some changes, concessions, considerations that had to be made from a lot of different standpoints in terms of stuff as mundane as how narrow the hallways are to the ability of the AI of the enemies to focus on one versus two players -- because it's no fun to play the co-op guy that the world seems to ignore -- to how the narrative of single-player story is told."