You don’t have to play the game in cinema mode.
Make sure to run the DirectVR memory scan after entering the game world (not in the menu). The scan can be started either with ALT+L or from the vorpX ingame menu. After a successful DirectVR scan vorpX manipulates the game’s camera directly instead of using mouse emulation.
Whenever a game supports DirectVR head tracking you see a notification about that in your headset when you start the game and also in the top left corner of the monitor mirror window.
Just in case: if you are using a Pimax 5k/8k, DirectVR probably will not work as intended currently.