Also the concept is stolen from "Battle Royale" which was a Japanese movie. The entire concept is literally ripped off. Seriously go watch the movie and you'll be as disgusted as I am.
This concept of making kids/adults/whatever fight in a gladiator type situation is as old and cliched as any concept. May I also point out that Battle Royale was made in the year 2000, where as Running Man, was made in 1987 and has a very similar concept. Battle Royale was (In my opinion) a badly made film that was for the most part uninteresting, with mediocre acting, and screenplay, the unoriginal plot hardly saved it. In my opinion, Suzanne Collins simply took an already established concept, and used it to tell her own story. She made new characters, a new setting, and told a story in a new way. Whether or not you enjoyed the way she told the story is up to anyone's private opinion, but it wasn't "ripped off" in any sense of the phrase. I mean, if you think this was a "rip off" then you should consider every spy film a "rip off" of the original Ian Fleming James Bond films. It's the same kind of thing. People use existing concepts to tell their stories, writers influence other writers.
If nobody used other people's ideas, we wouldn't have many films.
In light of this statement, which I completely agree with, I present a statement made by one of my favourite authors.
“Books aren't written - they're rewritten. Including your own. It is one of the hardest things to accept, especially after the seventh rewrite hasn't quite done it.” ― Michael Crichton
That being said, I don't advocate that Suzanne Collins really did anything ground breaking. The books where good, but not better than most, slipping at the final book. The film adaptations followed a similar patter, becoming less and less interesting with each installment. OK, but not great.