I've talked about video game books a bit before, but here is an article that really gets into what they are all about.  One quote in the article that really jumps out to me, and really is why I talk about video games books so frequently.  From the National Post's Mark Medley, quoting Hugo Award winning SF author and video game adapter Greg Bear:

Bear hopes the [Halo prequel] trilogy acts as a sort of gateway drug for gamers who might not be regular readers.
“These people haven’t read a lot of science fiction,” he notes. “And with the Halo trilogy … they’re being introduced to Arthur C. Clarke, Larry Niven, my own fiction — all that sort of stuff. The classic SF that I was raised on in the 1950s.”

These books aren't always very good (often not), but they are still worthwhile.  Read the article here.