- Executive Meddling: Eidos insisted that the game be developed with a console in mind, and that it be built on the heavily modified Unreal 2 "Flesh Engine" despite the amount of technical issues with it.
- Troubled Production: The engine the game was built on, a heavily modified version of the Unreal 2 engine dubbed the "Flesh Engine" was capable of great visuals, but it was a technical nightmare to work with. Disaster happened when the lead engine coder left partway through the project and left no documentation behind, leaving the rest of the team scrambling to fix critical engine issues. The Xbox also proved less powerful than the developers anticipated, and combined with the engine issues forced the developers to significantly cut down levels and take extreme measures to try and save on memory usage, such as shutting down the entire game and restarting it on every loading screen. These problems also affected the development of Thief: Deadly Shadows, which was developed concurrently with Invisible War and used the same engine.
- What Could Have Been: A May 2002 preview by PC Gamer showed screenshots that depicted wide open levels. It was also called Deus Ex 2: Invisible War, since there were apparently no plans for a console version at the time.
Trivia / Deus Ex: Invisible War