Nathan Regener - We are extending the engine work we did with Deus Ex: Invisible War, so you can expect that physics, lighting and interactive environments are going to be exceptional.

Warren Spector - I certainly HOPE players think of the game as "exceptional!" The nice thing about using an extension of the Invisible War code base - which is, as you say, a highly modified version of Unreal - is that we were able to use it to maximum advantage. I mean, we built Invisible War at the same time we were building the tech. The team couldn't exploit the tech to the max. The Thief team has the advantage of more time with a more mature code base and the results are on the screen. There are also ways in which the "Thief engine" differs from the Invisible War code - Deadly Shadows has a third-person mode, which is incredibly cool. I find myself switching from first- to third-person constantly, as the tactical situation warrants. I love the fact that I can do that. And the AI is substantially different from Invisible War. Thief's focus on stealth (as opposed to the DX "all things to all people" approach) really allowed the team to tighten up the AI and ratchet up the tension dramatically.