Alright, I figured it out. So the game has 3 major variables: Purity, Evander's heart, and Soren's heart. But mainly just Purity.
Both Evander's and Soren's heart variable are determined by who you call when you see the figure outside the window.
Now as for Purity, you start with a score of 5.
Being lewd, rude, violent or such will decrease points, while being hesitant, polite, "kind" and such increases it. E.g. complimenting Jon's outfit will increase it, while complimenting John's outfit will decrease it. I can write more precise decisions later in the evening.
Now, as for endings, here's what i found for the variables:
Ending 1: Purity over 10 TRUE END
Ending 2: Purity under 10, evanderheart true BITTERSWEET END
Ending 3: Purity under 5, choose gallery GUTLESS END
Ending 4: Purity over 10, sorensheart true BEAUTIFUL END
Ending 5: Evanderheart false or purity under 10 STARFACE END
Ending 6: Purity under 5, choose bedroom VIOLENT END
Ending 7: Purity under 10 and evanderheart false RETIRED END
Ending 8: E.g. Pick wrong killer DEAD END
I havent tested these out through the game yet, but ending 7 seems tricky, because you have to survive starhead but also Not meet the requirements to survive him later on, but Before the "facetime".. The idea being that you run away after the facetime..
Will keep combing through the code later but am in a hurry right now :D