It's a pretty nice game ! It lacks some music and sounds, but it's excellent

I don't think music would be appropriate. You're in a classroom. No music in class! The silence fits the theme of the game very well. Some clever sound effects like the footsteps of the teachers or ticking of the clock would be perfect, though.
I'd also like it if there was a small animation that played when a teacher sees you and the game ends. It's a bit jarring to just have the gameplay end so suddenly, especially since you can keep moving.
This is a pretty cool original concept, though. I'm always happy to see developers dreaming up new ideas, especially ones that feel like classic games like Get Out does. Good luck in the contest Jao, your game is great.
...word is bondage...