"Koushun Takami's notorious high-octane thriller is based on an irresistible premise: a class of junior high school students is taken to a deserted island where, as part of a ruthless authoritarian program, they are provided arms and forced to kill one another until only one survivor is left standing. Criticized as violent exploitation when first published in Japan - where it then proceeded to become a runaway bestseller - Battle Royale is a Lord of the Flies for the 21st century, a potent allegory of what it means to be young and (barely) alive in a dog-eat-dog world. Made into a controversial hit movie of the same name, Battle Royale is already a contemporary Japanese pulp classic, now available for the first time in the English language" ~goodreads
There is also a movie and a manga based off the book and if you search the two things on google you will find there is no shortage of gore.
I'm not one to compare one thing to the other. The Hunger Games is The Hunger Games and Battle Royale is most certainly Battle Royale. They obviously have similarities but they are still their own books. I think I might check out the Battle Royale book but I'm probably going to pass on the movie....looks a little out of control in the gore department.