Stop playing as soon as you start feeling ill. Just save and come back to it tomorrow.

Do not try to get back into it (or anything similar, like watching videos of FPS games) after a short break. Wait until the next day or later.

You should be able to get through games like that piece by piece. At least for me, I don't usually get sick from it. Maybe you get used to it as long as you stop once you start getting a little nauseous.

As for FOV, which seems to be the cause, I found a reference[1] that says the fov is 75 until you meet Alyx. (Wait, what?) Not sure what it is after that. There is an option in the settings to increase it between 75 and 90 (higher is better).

[1] https://steamcommunity.com/app/290930/discussions/2/61170199...

Two things basically eliminated the problem for me- first, like the other commenter said, increasing the FOV. The default is way too narrow, especially on modern widescreen displays. Adding another 10 or 20 degrees makes a noticeable improvement.

The other change was to eliminate the head-bob while running. There's a console command that takes care of that. Between the two, I went from nausea within a couple of minutes to being able to play for half an hour+ with no issues.

Hopefully this helps you, too!

This is normal, and imho is one of the biggest challenges facing the VR industry: as people age, they are less and less able to do VR.

Its because you're getting older and your eyes are not as level as they used to be. Our brains are wired to correct the differences in horizon that each eye sees, and applies a filter to the 3D inputs so that we don't get motion sick. As we age, our eyes physically change position, and the brain has to do more work to make this horizon correction - with 3D games, it no longer has all the inputs it needs to do the correction (because 3D games aren't really 3D but rather an imitation of it on a flat plane), and thus you start to feel motion sickness more and more.

https://en.wikipedia.org/wiki/Depth_perception#Disorders_aff...

[0] https://ca.ign.com/articles/2004/11/24/half-life-2-motion-si...

Changing the fov helps.

That was the effect it gave to me too. I believe it's due to the the player moving the field of view rapidly: I played this game less than a year ago and experienced none of this. Being in control helps a lot as the brain knows we're moving and expects the view to change.