Smart Head Track is a head tracking app that supports OpenTrack. 

It is designed for use with action game and simulation game.
It tracks the position and orientation of your head without extra device.
You only need the app and OpenTrack open source software on your PC.

It will work with games that supports FreeTrack or TrackIR protocol, such as
- Microsoft Flight Simulator
- Microsoft FSX
- Euro Truck Simulator 2
and more

Instructions on the PC
1. Download & Install OpenTrack on your PC. (https://git.io/JUs2U) 
2. In OpenTrack, select 'UDP over network' as input source and 'freetrack 2.0 Enhanced' as output
3. Do not click START yet.
4. Make sure the UDP port of OpenTrack is open on your PC firewall. (Default port is 4242)
5. Find the IP address of your PC.

Instructions on the App
1. Open Smart Head Track App
2. Set up the IP address and port.
3. Position your face inside the camera screen.
4. Click Re-center to configure offset automatically.
5. Click START both on the phone and PC.