Story: 10/10
The plot was captivating from beginning to end, with absolutely no filler or gray areas. I want to say more, but I'm not sure I should. All I will say is that if your into the "Psychological Game-play" genre, this is definitely worth a watch. Also, as I've noticed others have mentioned, this really isn't all about terrorism. But I'm sure you'll discover that for yourself when the time comes.
Art: 10/10
The artwork was phenomenal. There were little to no areas that I could point out where the art was lazy, and the intentional use of dark shading and pale colors for the characters was well played. Only specific scenes and objects (the sky, for example) were given vivid colorization, and with an underlying purpose. Additionally, it uses those gradients that animators love so much to throw in nowadays (usually into shoujo/comedy anime) but again, only in very specific situations, like in the characters irises, which I found interesting.
Sound: 10/10
I'm listening right now to the OST. It's really nice, and the animation in the ending that goes with the ending song is just...sugoi. My favorite part about the soundtrack, though, is that when songs with lyrics are used, they aren't only Japanese--they're English and WAIT FOR IT--Icelandic! Which also ties into the plot (just made a revelation). This just keeps getting better and better.
Character: 9/10
Okay, to be honest, I didn't really pick up on this until reading other reviews, but the certain characters really aren't developed much at all. The reason why this didn't occur to me/why I don't care, is because it really wasn't relevant AT ALL to the story.
SOME SPOILERS, KINDA:
The only characters whose backgrounds really mattered were Lisa (minimally), Twelve, Nine, and Five, and they were explained to an extent that made sense--at first, you know hardly anything about them, but that was how much the world knew about them. Their pasts were meant to be concealed. The only character that could have used more of a backstory was Shibazaki. They started to say things about his past, and just sort of dropped it.
Enjoyment: 10/10
No explanation. See above for details. (I mean, honestly, I enjoyed it to the extent that a series like this should be enjoyed, which is why I give it a 10/10)
Overall:
10/10. Despite the tiny character development flaw, I found this to be so enjoyable and well made.
