Detective Harry Callahan is one of Clint Eastwood's most enduring characters, and starred in some seminal action movies back in the '70s and '80s. Eastwood's no-nonsense cop would inspire countless clones in both movies and video games, and back in 2004 Warner Brothers decided that it was time that Callahan was resurrected for an entirely new audience.
Dirty Harry Extreme was to be an action video game produced with the intimate involvement of Eastwood himself. It was slated to appear on pretty much every platform of the period, including the Wii and DS. However, Warner Brothers halted work in 2007 because it was displeased with progress, and attempts to restart producing failed. The project was eventually cancelled when the publisher decided that there was no way a reasonable game could be created. Years of development, cash and Eastwood's valuable time had been wasted — the Hollywood legend was to lend his voice to the game as well as act as a consultant, and apparently spent a significant portion of time refining the script. To give you an idea of just how big the project was, it was also set to feature the vocal talents of Laurence Fishburne, Lucy Liu and Gene Hackman.
Envisaged as a cover-based shooter with a unique reputation system which made enemies react differently depending on how trigger-happy you were, Dirty Harry Extreme was an ambitious undertaking. While the Wii version would have been a variation of the PlayStation 2 game with motion controls attached, the DS version is rather more interesting, and would have been built from the ground up.
You can read the entire story about Dirty Harry Extreme's development and subsequent cancellation here — in the meantime, there's this trailer which was shown behind closed doors at E3 2006. Clearly pre-rendered, it shouldn't be taken as gameplay footage, and was created by an external studio. Even so, it gives a hint of just how amazing a video game starring Harry Callahan could have been.