So, I'm a huge fan of the visual novel this anime is based on, and I just started watching the show. It's a murder mystery, basically. The antagonist decides to recreate a murder mystery novel by trapping 15 students in a school, and the only way to escape is to murder another student and get away with it. Granted, the main character is a bit of a dull piece of shit, but the supporting cast are what make it so interesting to me. Especially Kyoko. >_>
Also, the game (and its sequel) are by the people who did Virtue's Last Reward and 9/9/9.