The Stanley Parable (Book edition)

But here was the proof. The heart of the operation. Controls labeled with emotions: 'happy' or 'sad' or 'content'. Walking, eating, working... all of it monitored and commanded from this very place. And as the cold reality of his past began to sink in, Stanley decided that this machinery would never again exert its terrible power over another human life.

For he would dismantle the controls once and for all. And when at last he found the source of the room's power, he knew it was his duty, his obligation, to put an end to this horrible place and to everything it stood for.

The on/off button.