The Running Man: by "loosely," they mean that if the book and movie didn't have the same title, you might not realize that there was any relation. I enjoyed both, but the two have very little in common.

In the book, for starters, he volunteers for the show, because he needs/wants the money. Instead of being sent into a studio labyrinth to defeat the comic-book-hero-like people, he has to survive out in the world for a set number of days, while being chased by a group that are more like bounty hunters.