[SPOILER]
I have to say I really did think Zach was going to be Mc's double personality or smth, because in the end there was really nothing that made Mc essential to the plot (more of a self insert than anything central to the story) or special in any way to be spared by Zach. At the end I was asking myself the same thing Braxton and Artemis did once "Why did everyone else died but Mc?", even in the bad endings either Mc was convenently "sleeping" throught it all or they just were never mentioned. (dude this would fit so well, in my head at least haha)
Hopefully vitaeo makes a sequel or prequel of this game because besides that the plot was interesting, the characters lovable, and overall well writen, I even hoped for a yandere twisted romance with Zach because this dude sure have layers that i wish we could take more time to peel.