As for concept of apocalypse cause, it is new and could be developed further. But that is all the good point to this drama. I recommend you to watch if there is season 2.

Here is the thing:
For a drama with only 6 episodes and around 30 minute long, you know there is not much time for most characters to develop. Most drama with total of around 4 hours screen time only focuses on at most 2 or 3 characters to make them relatable. For this drama though, who exactly am I trying to understand? I have got the monks, the police, the teenager, the bullies ...

Is it impossible to get most characters to have personality conveyed through short screen time? No. Train to Busan is a movie that is around 2 hours long and we know even the side characters' personality. Too many unrelated point of view cut scene - I get that everything is happening at the same time but how about we focus on one character's at a time instead of jumping from being admist the chaos to being outside the chaos. Giving one POV at a time then rewind to give another POV at the same time explains more to viewers than small splits.

All of us are dead - plenty screen time - is a great example. We got things done in the school then we jump to things done outside. This drama does not even have enough screen time but it tries to fit way too many background that made every characters feel unimportant.

The casts actings are really well done but the story did not do them justice. I think my rating is already generous for this drama.