They work REALLY well. Ever since getting my HTC Vive in 2017, and recently upgrading to a Valve Index, I haven't played a non-vr FPS game.

Check out

  PavlovVR (CS:GO ripoff): https://www.youtube.com/watch?v=OPMllOHfxCc

  Serious Sam VR: https://www.youtube.com/watch?v=3-Qgx70_P8E