opentrack tracks your head movements allowing use with games, flight simulation software, etc.

opentrack is a fork of FacetrackNoIR continuing with the development. It supports many different ways to track your head's movements; you can set up a piece of paper that you print special symbols and a webcam. It will then track the symbols. Or use the traditional face tracker where it will follow your face. You can substitute a smartphone for a webcam if you do not have one available.

opentrack allows for output shaping, filtering, and operating with many input and output devices and protocols; the codebase runs Microsoft Windows, Apple OSX (currently unmaintained), and GNU/Linux.