Oh Alice, you have such an intriguing overarching scifi thriller mystery, why that messy ending that is hard to overlook? Oh well, the writer already showed his fixation beforehand, I was just too stubborn to drop it.

Spoilers:
Joo Won is good in action, I really wished the show just stuck to be a straightforward thriller, and did not insert all those almost 'otp' scenes between Jin Gyeom and Tae Yi. It's plain weird and the worst part of the show for me, which is sad as they are the main leads and the focus of the show. Why show?! Such a waste of Do Yeon and Min Hyuk too.

Jin Gyeom was a bit uninteresting until that twist, which of course Joo Won always delivers. He is wasted on goody goody straight roles. I felt the show lacked the right comic actors too. I also felt more scared with that young evil Jin Gyeom, than the old teacher one (probably because of that weird makeup). 2020 Jin Gyeom warring with young evil Jin Gyeom inside 1 body was so fascinating, the show should have stuck with it more.

Well, all those can be forgiven, but that last part where they have to force the Jin Gyeom-Tae Yi OTP when it doesn't even make sense anymore, just NO.