Detention

Detention is a point-click sidescrolling horror adventure where you fall asleep in a class lecture and wake up to an empty school that has roaming zombie-like creatures that you have to hold your breath and/or evade to pass, all while you are looking for clues as to where everyone is and how you can get out of the area (typhoon reported coming, but bridge is out).

That's when it takes a darker turn.  You're character ends up getting caught and then hanging upside down from the ceiling and you start playing as the girl you found.  Apparently he was NOT dead, however - as one of the notes you uncover shows the draining of blood into a bowl, which you ... do to the guy who found you and was hanging.  He opens his eyes in wonder as you drain his blood into a bowl, but not for some demonic purposes, simply to get an imprint of a code from the desk of another student.

Wow.

All the while you are picking up notes that give clues as to how to deal with the various zombie types, but also a bit of the backstory to the characters.   I stopped playing because I don't like a "try clicking on everything with the paint bucket until something works" type puzzles, when they work they work, but wandering through multiple levels looking for what you missed is a yawn.

I did read the Wiki to see what was actually going on, and it seems quite good.  Spoilers, but apparently the girl is going through stages of purgatory after a suicide based on the guilt she had over the events that led to it.  Something about reporting the smuggling of banned books and a mistaken love triangle.