English isn't my first language but I'll try hard to make this understandable.
To summarize the review I just wanna say that while this is an entertaining action show about an ensamble of funny and quirky kids getting surviving the apocalypse while showing a lot of cute moments between them, the best part about it it's that it made me want to read the webtoon, and it's much better in all senses, a beautiful but depressing ride and that's why I think they made changes to be closer to Sweet Home or All of Us are Dead(Specially this one).

It's the second time i write a review and my thoughts are similar to my first one (Sweet home), these webtoons might be fictional apocalypses with a lot of action but what made them good was the psychological and character building aspect, while their drama counterpart makes changes to make them more entertaining for the public but throws away the essence of the original work. Like in Sweet Home, I think some people will say that it's not fair or that you shouldn't say the drama is bad just because it's different from the webtoon. The problem isn't that it's different, but that they changed it for the worse.

On the good side the CGI and action sequences were really well done, I liked the casting for the characters and most of them felt close to the webtoon inspiration, also both of the main soldiers are more fleshed out here and I liked that .
Now to start on the bad side, the first thing i have to say is don't try analyze things too much because you will realize about how a lot of scenes and situations don't make sense at all, I guess the director and writer side was lacking because they went too hard on the immature brats that are too preoccupied with their grades and their dialogues can be very cringy at times, they changed the spheres to fit their action heavy show but then made them feel like billions of were attacking at every time while the kids ammo was infinite, I read comments saying that the aliens treated the kids different from adults and honestly it shows a lot.

I will spoil a bit of the webtoon because after the changes made to the show, I think the second half won't follow the original. In the webtoon the plot armor for the main cast isn't as obvious, some of the kids die and they aren't the dramatic beautiful sacrifice kind, they are fast, unexpected and have 0 beauty. The webtoon is more about how this group of kids are thrown to war and the scars that it leaves on them physically and mentally, but also how they learn to normalize what's happening around them and how scary that is.