We'd like to thank The Hunger Games for pointing out one of the inherent problems with the ratings board. The novel itself would probably be rated R. Suzanne Collins wanted to emphasize the brutality not only of the Games, but of the Capitol itself. This leads not only to messy ends for a number of Tributes, but a much more horrifying version of the hounds at the end. (In the book, they were mutated from the corpses of the other Tributes. Ick.)
Unfortunately, making the film R-rated would prevent a big chunk of the core fan base from going to the movie unless they brought their parents (and seriously, who needs that?) So the filmmakers were forced to deliver R-level intensity with PG-13 blood and guts, a harder balance to strike than you'd think.
Director Gary Ross came to the rescue on that front, using handheld cameras and sharp editing to bring the intensity to the Games themselves. You can sense the knives flying and the bodies going "splat." By and large the trick works pretty well, keeping the violence down while still implying the savagery of the government that demands it from these poor kids.
The film doesn't suffer unduly from the changes that make the story a little bit gentler in order to fill those seats at the theaters.