Unseen64 has been knocking it out the park recently, as far as games that never saw the light of day go. Going through a publisher's failed projects and seeing what they dig out is fascinating and this one certainly will turn heads.
There have long been rumors of a Dark Knight video game that was meant to come out around the time of the movie. The YouTube channel have lifted the lid on the project and where it was before getting canned. It really is a fascinating look at the production.
Take a look here:
We ended up getting Arkham Assylum around the same time, so it is hard to feel hard done by here, but still. I'd have been interested to see what the game for the movie would have looked like.