I watched this without seeing any reviews, ads or even trailers but 've read that this show was promoted as "unscripted" reality-tv. If that's the case, then the promotion is grossly misleading. This show is neither a game or even reality TV. It's really a work of fiction in which the cast play themselves and are improvising the dialogues. And the final result is pretty bad.
There's a huge flaw in the whole concept that makes it unable to work, I'm surprised that it wasn't obvious for the producers : the cast can't hurt the "zombies" since they obviously know that those are just regular people. So you're stuck with "characters" who can't do what one would normally expect them to do in such a situation, which is to bash the heads of the zombies or at least try to neutralize them as violently as possible (set them on fire, dismember them, whatever...). All they can do is flee, which is ridiculous.
I wanted to like this show but really the only thing enjoyable is the little moments when the cast can't help laughing at how stupid the show is. Oh, and Lee Si Young is such a milf, my god. I hadn't noticed that when I saw her in Sweet Home.