You appear to be wrong.

geekwire.com/…/behind-scenes-half-life-alyx-valve…

GeekWire: So you’ve been working on this _(HL Alyx) _full-steam since 2016?

Robin Walker: We started in February of 2016, I think, with a small team, and we brought out a small prototype. Then people started to play that, understood what we were trying to do afterward, and started joining up.

We had 80 people on the team when we were about midway through. The exact size of the team I wouldn’t be able to tell you. The way things work at Valve, people organically join once they’ve finished up what they were doing before, and if what you’re doing makes sense to them.

So it was always full steam ahead, I guess, but not in the sense that all 80 people were there from day one.