I loved the first part so I don't know how the writer/director failed to end this series well in such a terrible way. Spoilers towards the end.

The 7th episode starts off on a high note and a time jump. Our students are far better at killing the aliens and have developed good survival kills. This episode is a bit fun to watch after all the dread, fear and sadness of the first part. But we don't know why the students are living off base? Where did the other soldier in charge (Won Bin) go? None of it is explained.

Getting credits for their time served for the CSAT is what was keeping the students fighting and this is still a major discussion in part 2. What doesn't make sense is half the students still want to go home. It's not possible that their memory failed them of how they nearly died at their school and just barely made it out alive. Because why would you leave a place where there are less spheres and thus less danger? Especially since the first part also showed them how spheres were about to target a place where families were put up as a safe house. So it's very likely that that many of their families may have been attacked.

It also doesn't make sense that none of the adult soldiers are in the picture anymore. Why didn't they give them the opportunity instead to talk to their families over the radio? Or at least provide some kind of update. Missing them made them want to just run away even more. So as the series went on, it got more and more unbelievable.

At one point they have to deal with prisoners left behind. The biggest wonder is how did these people even survive without any water? They seemed to have a lot of energy despite being starved for days. No logic there. Only one of the prisoners talked sense on the condition of humans and humanity.

Themes of distrust are a major component in the final two episodes. Hiding the truth never ends well. And this is where the downfall of the show began. It's like the plot took a sudden detour and crashed into a wall. Details with spoilers below.

MAJOR SPOILERS NOW
- How was electricity running at the theme park for the rides but they couldn't heat their food? And all the food stored had gone bad?
- How does a scrawny kid having a psychotic break manage to tie up a body with rocks and drown it in the ocean? Where did he find ropes and a rock that heavy? The kids almost immediately ran there. How did they not catch him in the act and how was he not soaking wet?
- The main reason this show is a disaster is because they turned it into a sexual assault and school shooting episode rather than stick to the the main plot. All those "good guys with guns" lost their lives because of the "one bad guy" they didn't see coming. Would have been a great show but this is not why we were watching. They really did them all dirty with this plot move.
- And to add insult to injury, the aliens were all quickly destroyed soon after. No one talked to the students that they were even close to developing proper weapons which would have given them hope and a boost. And in the end, they didn't even get told if their points would matter. Plus, they made the exam extra hard.
- Honestly the ending was so bad that it would have been better if it were all a dream.
- A good alternate ending would have been that they find out he was the killer but then an alien actually comes and kills the psychotic student. And they kill the alien, mourn their loss and survive.

SPOILER FREE
The biggest plus points of this show are:
- The CGI is still wonderful
- The bonding between the students during their lighter moments
The only reason why I even gave this part any points.

For fans of the first part, this one will really leave a bad taste in your mouth so brace yourselves.

EXTRA CREDIT SCENE:
There is a scene/song at the end of the final episode. Almost missed it because I was so upset with the ending. You can be the judge of how you feel after this bit.