This film was fine - I spotted 4 Flaws.

One other flaw I caught... Will, Tommy, and Sadie had gone out to the back yard at least once during the party. Then when Eden asked at the end to take her outside they went. But all the doors and windows were supposed to be locked. So how did they easily get out those two times? That's the only thing that bothered me about the movie, otherwise I thought it was pretty good.

To answer the question of having everyone die with you, the other guests presumably did go through a trauma because the child died at a birthday party they were all at. It wasn't their child, but they were all very close friends at the time and I would imagine that affected them deeply.

I also agree that her shooting herself in the stomach was probably symbolic for that reason.

How were the four people that were 'in' on it not able to find Kiran and Will in the closet, because the skinny girl clearly knew they were
- as they showed when they walked out the room, skinny girl was dying herself and had collapsed on the sofa. She didn't have the energy to alert the others and perhaps didn't care since she was done anyways.

-When David is about to go up the stairs with a knife in his hands, Will shouts 'We got a gun' (although this gun is empty). However, almost immediately after that, David gets attacked by the gay guy who is unarmed, which wouldn't make sense because he presumably also knows that Will has the gun and therefore the upper hand.
- I don't think gay guy cared. He wanted revenge for his partner who was shot by David.

-Why did Eden shoot herself in the stomach? Was she actively trying to die in agony? I have a theory myself: She lost her child which originated from that very place, so it symbolizes the source of her pain if you will.
- yeah you're probably right about that. Or she was so grief stricken she wasn't thinking straight.

-The cult ideology never rationalized why there should be other people dying along with you, presumably even people that did not go trough horrible traumas. Kira and the gay guys did not seem mentally scarred for instance. Perhaps this explanation simply got left out but to me it seems imperative.
- according to the cult philosophy, dying together was special. They probably thought they were doing the randoms a favor