The script was able to dissect multiple levels of depth regarding humanity, when there's competition to limited resources, how would humans handle a fair distribution of the wealth, while some are just hoarding resources due to psychological needs just because they can, or those fighting for scattered leftovers who are struggling to survive. When humanity is put into the test, human beings will have to choose between action with conscience, or survival at the cost of moral values. We can't deny that this is the raw human nature no matter how we try to conceal it or constraint it, because we were once a beast that scavenges everything we could to survive this shitty world. The movie has paid an incredible amount of attention to details into this concern, and the post disaster survival theme setting fits right into the situation it needed to achieve such a chilling effect. The cinematography and acting are of course top notch, pacing also helps a lot to hold the storyline together, this is really one of the most ironic dark humor Korean movies ever made.