Wanna give y'all heads up that even with my TrackIR Pro+Vector Expansion (basically a very old version of TrackIR), the shareware version (demo) works like a charm.
Full version already bought :-)
Thanks!

I'm still not sure how TrackIR can be useful. You move your head away from the screen and the view on the screen tilts/rotates in the same way. But now you're not looking at the screen… Maybe it would work better without glasses. ;-)

Not looking away. You keep your eyes at wherever you had your eyes previously (e.g. center of screen) and then you turn your head *slightly* in some direction whilst not looking somewhere else with your eyes. The software translates that little movement to a big movement ingame.
Gotta try it. Feels natural after you know what's happening.
Real VR-Headset would be better but with this you only have to wear a baseball cap with the IR markers on them.