When this went through the cinema I think I discounted it. A film about roleplaying and games probably would probably be too full of inacuracies. However it turns out to be much more about autism. I'd liken it to The Curious Incident of the Dog in the Nightime.
This book is set in a universe where nano-technology has transformed humanity. Bodyshape has become a matter of fashion and human necessities are taken care of. Crime is all but unknown except that the main character is a murder now being employed to commit a mass murder. A reasonable read, I might check out some of his other books.