Given the previous history of the Half Life franchise, we're most likely in for a FPS Shooter with lots of environmental physics manipulation through a new VR control scheme, utilizing the Valve Index (and other VR controllers).

Given what other people in this thread have mentioned, you will not be moving within a virtual space via VR inputs with full body mapping to in-game movement, as that's a recipe for getting sick.

Given my experience with VR and playing games that required a fair amount of movement, Superhot VR and BeatSaber, the space needed was just enough to stand up, and move my arms around. I am really unsure of why this space requirement issue keeps popping up. Unless you're doing full room mapping, which I highly doubt this game will utilize, I cannot imagine that most people with an entertainment center or with a desk dedicated to their PC, don't have enough room to stand up and move their arms around...

The space requirement issue keeps coming up because not everyone lives in the same sized house. Just because you have ample space to stand in your room waving your arms around with a headset on doesn't mean everyone else does.

I'm having a hard time imagining a living situation where you don't have enough space to stand up and move your arms. Could you describe one? At worst it could only be a tiny number of people, maybe people living in their cars, and definitely not the target audience of electronic entertainment.

You need enough space to stand up, stick your arms out, and move around. Considering the average human wingspan is 5' 9" for men, add another foot and change on each side for a safety factor so you don't smack things if you lean a bit, and you end up needing a playing space that's an 8' diameter cylinder, and that's just for seated/standing experiences, not room-scale. This 8' cylinder also needs to be next to a computer, or you need to run a lot of cables. I live in a 3 story row house and the only space I have with enough room is my kitchen, anywhere else in the house and I'd end up hitting something.

Standing up and moving your arms has much lower space requirements than standing up and moving your arms while blindfolded and under a barrage of industry-leading illusions engineered for maximum distraction.

There's boundaries that the VR will put a red wall on screen if you approach. Setting them up is part of the installation of VR. I helped a friend setup Rift Oculus a while ago in a very small living room. Like bedroom sized living room. I've also played VR while sitting on a couch. Room is not an issue unless you play in a closet.

In a typical users playspace you're always near enough to the boundaries that they're visible. And speaking from experience, you do not want your VR setup within several feet of anything nice, like your television or hanging wall art, even if they're outside the boundary. As a good game of Gorn is guaranteed to make you run past that boundary and punch a nearby object.

Yes you can play some VR on a couch, but not Superhot, not Gorn, not Space Pirate Trainer. Very likely not Half Life Alyx.

I've used my VR setup from within cramped confines, but it's not something a non-enthusiast will do.

Edit: Also were forgetting a very important point mentioned above

"I'm not going to [...] lock my dogs outside just to play a video game."

There's a big difference between being able to stand up and move your arms, and being able to stand up and move your arms anywhere without looking while being certain not to hit anything.

At least for me, in all the spaces I have computers, if I stand up I have some stuff or shelves within arm's reach, because I want that stuff to be accessible - but that makes those spaces unusable for VR, because I'll hurt myself those things or myself if I'm swinging around without being able to see what's there.

I have ample space available, but I have gotten so lazy in VR that I tend to confine myself to a chair or just a small place to stand. Teleport locomotion is my favorite. I really don't feel like I'm missing a whole lot by not walking around much.