Ko Ja Yoon is a fascinating main character, and she makes the film intriguing despite the world-building being sort of thin and the plot being generally predictable. I think the most impressive thing is that nobody in this film is stupid. When strangers are creepy and weird, characters — both side and main ones — recognize it and act accordingly. It was refreshing.

In fact, I'm pretty impressed with the more down-to-earth elements of this film actually; the dynamic between KJY and her family and friends were really interesting, and I want to give a special shout-out to Go Minsi, who really sold her role as the spunky best friend.

On the other hand, while Kim Dami and Choi Wooshik have fantastic chemistry together — the fight scene between them is one of the best moments in the film — I feel like I didn't feel fully convinced by the main scientist or the other "powered" people. Going back to the thin world-building, I think the environment of the government facility, the motivations of the people in charge, and the backstory of other experimented people were just not altogether there.

Overall, it's still a quick, engaging watch and I can see why it got so popular.