I REALLY like the writing in this. You've got a good way with words and characterisation. Big respect.
Constructive Crit: Pleeeease don't make meta horror a feature of every route. By which I mean, "oh my god, we're all characters in a video game!" or "you're not my real brother/best friend/main character!" Doing that in one route could be cool, but that sort of 'meta' element, where the characters are distressed that they're in a video game, has been surprisingly common in yandere games already. John Doe did it. Parts of Your Boyfriend even hinted at it afaik.
So yeah, great start. Would love to explore each route (except for the sadistic science girl. maybe she uses her tech knowledge to overcome the meta horror of being trapped in a video game. who knows. I'm just spit-balling.)
Big props! Would buy! (Especially if the final version is NSFW ;)