Many games and simulators nowadays support headtracking. That means, that a tracker determines the pose of your head (rotations and translations, or 6DOF). The headpose is then amplified and filtered by a program (for instance FaceTrackNoIR), so a relatively small movement of your head is translated to a larger movement in-game. The program sends the manipulated headpose to the game, which shows this movement, by manipulating the camera. Many gamers already use a headtracker, most of the times one using a webcam.
FacePoseApp is an App that turns your smartphone into a smart face-tracker. It offers some big advantages over face-tracking with a webcam: the user does not need to buy a webcam AND the PC running the game does not have to spend valuable CPU/GPU-power to track a face. In addition, many smartphones and iPads (from iPhone 6S and up) support tracking at higher speeds (above 30 fps).
FacePoseApp sends the 6DOF to the external program over Wifi or USB (this feature can be unlocked, by upgrading the App). Without the upgrade, the user can test the performance of the tracker and the communication to the PC