Interactive Movie, Which sensor?

hello there,
we are a couple of students who would like to get some suggestions about which sensor we should use for our project. We are going to make an interactive movie, in simple terms the idea is to allow the participant to have influence upon the movie while it plays out. The movie is going to be controlled through some kind of sensor placed upon the participant. So we need a sensor that tracks the motion of the participants movements, this could be an arm, or hand gesturing for instance.We could of course use kinect, but we would rather use an arduino sensor. Do you guys have any idea of an sensor which fits our requirements?
thanks in advance:)

The three major options are Accelerometer, Rate Gyroscope, or Magnetic Compass. All three are available in chip form.

Accelerometer: Detects changes in speed. When speed isn't changing detects orientation relative to gravity.

Rate Gyroscope: Detects rate of rotation.

Magnetic Compass: Detects orientation relative to local magnetic field.

Many people use a Wii controller Nunchuck which includes an accelerometer and several controls. It is easy to connect to the Arduino.