the adaptation covered almost everything; there are slight changes here and there, but they also changed a few major plot points.. if they were to create season 2, that would mean new and original content.
the biggest changes are the cause of the outbreak and the ending. characterization is also different, especially with cheong-san. (oh and gwi-nam does not have a missing eye; he is missing his genitals lol)
tl;dr: adaptation is good, but the manhwa is also worth looking in to! just note that the manhwa is more ruthless and grittier than the adaptation.
