App with motion detection

When a user "kills" hunger, he kill a monster on the app screen. user chooses among three levels of hunger. If the user is making the move to chew, the monster takes punches. When the user stops the movement, the punches stops too. The monster dies at the end of your health I need source code and demonstration of chewing motion being captured. This app is very simple, but the face motion is very subtle and the app must respond quickly.