I was thinking earlier about how you get a lot of film to video game conversions, and a lot of book to film conversions, but not a lot of book to video game conversions. The only ones I can really think of are the Hitchhikers guide to the Galaxy text adventure game, and a couple of Discworld games. But then again, Hitchhikers was never really one format to begin with, and Terry Pratchett is notoriously picky about who can do what with his books.
I say this because I was thinking about how the Hungry Cities series of books would work as a game.

I've just finished reading them, and they honestly blew me away. They're about a post-apocolyptic world where leaders have decided to move their cities around to keep them from being attacked. The cities have huge jaws on the front to devour smaller towns or static settlements. The materials they gather are then sorted by people in the gut and used to extend or maintain the city. Due to the movement of the cities, the earth is constantly churned up, and no vegetation grows. A group called the anti-traction league have settlements in the Himalayas, and want to restore the Earth to its green state.

There is a lot of scope for a game here, either sim city style, managing your moving city: Where do I use the new materials? Where should I hunt next? Who should I trade with?
Or perhaps as an adventure with the two main characters, Hester and Tom. Between the first and second books they go adventuring on the Bird Roads - paths taken by trading airships. This leaves a lot of scope for players to visit all the cities they could wish to without upsetting any plot balance. You could play through the first book and then adventure in the Bird Roads.

This sounds so fun. I'd play it! Fortunately, Wikipedia says that "It's rumoured that Peter Jackson has displayed an interest in making the Hungry City Chronicles into an episodic video game for Xbox 360." But then again you can't trust everything on Wikipedia.