I Am Experiencing A Major Writer's Block

I am trying to make a game, and now, I have no idea what to write,

Okay, so, due to my love of Otome Games and Visual Novels (and of course, Yanderes), I have decided to make one. I called it "Call Fate". It's about a girl who received a phone call from a stranger, telling her he'd kill her on August 31... but she didn't die on that date. Instead, her soul got stuck in someone's body. And that someone is a target to many murder mystery.

So, other than the obvious love story, the game also wants the player to figure out who the murderer is. For me, the main purpose of this game, other than the romance, is survival. Since this is a story full of attempted murder, the player must make the right choices in order to not get killed.

I have finished the Common Route. I am not that proud of the script since I think it still needs a lot of revision. But then, as of now, I really have no idea how to proceed, lol. I am working on one of the routes and I have no idea what to write next.

*Sighing* Just when will I be able to finish this game?! *Sighing again*