There are two possible ways:
A. Displaying the undistorted game:
1. Open the vorpX ingame menu with [DEL]
2. Go to the display page of the ingame menu
3. Activate “Direct Mode Show Original”
B. Displaying the stereo view like seen in the headset:
1. Run the game windowed
2. Open the vorpX ingame menu with [DEL]
3. Go to the display page of the ingame menu
4. Activate “Direct Mode Show Mirror Window”. This option is only available when running a game windowed.