Move the mouse horizontally to move Stacey. If you touch the Shoulder Angel, you gain a point. If you touch the Shoulder Devil, you lose a life. If you don't have a single life, you lose.
Credit to BYU, Studio C is amazing. 1.1 UPDATE: Added music. 1.2 UPDATE: Made the game a little easier by taking away the thing that makes the Shoulder Devil take away points.