Spoilers, if you care bout that kinda thing.
I'm gonna level with you. This is mediocre.
You got a couple jumpscares, two buttons, then two or three sidescrolling levels.
Best thing you got was that teacher jumpscare at the beginning, not a bad start to show the sudden movement, jolting you from the expected "movement" of pico's school.
Couple problems stem from your choice of subject. EXE games in general are not scary to anyone who's seen a couple jumpscares in my opinion, and this is no different. It's exarcebated by the backdrop of pico's fucking school. Nice villain dialogue you got, too bad it's undercut by the "Chicks with dicks, 2x the fun" poster with a piece of shit visible right underneath it. Makes it hard to take this seriously.
Speaking of that dialogue though, it actually kinda lost me own it's own merits too. The setup was fine, talking about a different reality where you didn't show up, but the fuck do you mean the shooting didn't happen without me there? Dude was set on violence with or without me.
The jumpscares didn't work, and the existential shit didn't work for me, so I don't got anything to be scared of. Ultimately I'm just left with the gameplay, which is just alright.
Needs work, but I might recommend trying your talents with different source material. This concept makes it extremely difficult to produce even an "okay" result in the end. I see good tricks and programming from you, and I do hope you continue making stuff, whether it's this or otherwise.