First of all this drama was awesome. Ost , acting, director all was good.
1) this story involves a pyramid structure of bullying.Though our antagonist says this is everyone's game but Those who are from powerful family, are popular will end up getting grade A . And from grade A to grade D is allowed to bully grade F . 3 grade A , 3 grade B , 6 grade C , 12 grade D and 1 grade F .

2) I liked the fact Sung Sooji isn't a pushover , like everyone she tries to avoid problems or bullies. But end up getting grade F and tries everything to get rid of this game . And she ends this game .

3 ) the thriller is great, like--- mind games , violence, betrayal everything is top notch.
Then why didn't I gave it 10/10 ?
Reason 1: Getting everything on her side was a little weird like Woori's brother as helper and hacker( it's okay cause psychopath like Harin is uncommon too ). Though the video was published, they never revealed the rules or published something extreme. the violence except kim Dayeon beat her classmates wasn't shown in the video/ live stream, It was easier to get rid of the accusations of Baek Harin through Baek group's power and influence.There are always some violence in school but without knowing that pyramid shaped ranked bullying why would the reporters will report ? ( Baek Harin never bullied or did something extreme in front of camera so people should have been called Kim Dayeon psychopath instead! ) It's okay though, the drama was outstanding .
Reason 2: what about Kim Dayeon's domestic abuser dad ? I know it's satisfying to see her get beaten up but she became violent bully cause of constant abuse .

4 ) this drama is great and I highly recommend it.