If your goal is to play a complete game, The 2015 build will bore you in under 15 minutes. It is a tech demo with bugs.
Animations in 2015 were incredibly stiff. Ayano’s running animation was more of a floating glide. The "laughing" animation (to lure students) looked unnatural, and the murder animation was a single, repetitive "stab" that didn't sync with the character models properly. yandere simulator old builds 2015 download