This is a thriller with some what similar premise to hunger games. However it is more gritty, fast paced with lots and lots of blood. The mysterious game master and brutal games keeps you guessing and pulls you inexorably into this world. I was able to watch it knowing that it is complete fiction. It ended at a great cliff hanger and has been renewed for a second season. Great acting, story and production. It warrants a one time watch if you are able to tolerate gory scenes.
PS: When I watched it on Netflix, I turned off the English audio and watched the original Japanese version with English subtitles. The English audio dubbing felt strange.