Half-Life: Alyx was conceived as a VR title first, and a Half-Life game second

Half-Life: Alyx, Valve's upcoming VR entry in the Half-Life franchise that was revealed earlier today, is a team effort across multiple developer teams at Valve, including former members of Campo Santo.
In a https://youtu.be/-9K0eJEmMEw, Valve developers David Speyer, Robin Walker, and Dario Casali discussed the conception and creation of Half-Life: Alyx, stating that it had been conceived as a VR game first before it was thought of as a Half-Life game. The goal, they said, was to come out with the big, all-encompassing, AAA, high production value VR title that the platform was currently lacking.
"There are many reasons why it's still hard to justify building something of that scope in VR," said Walker. "We felt like that was a role we could fill, because we can invest in longer-term strategies around putting more effort and time into something than we may expect a return from an audience like VR."
During early experimentation, the team considered both the Half-Life and Portal IPs as options, but rejected Portal due to the likelihood of players becoming sick while using Portals in VR. They then began playtesting different concepts using recycled assets from Half-Life 2 and trying to see what mechanics made sense.
Walker added that while there was certainly pressure to do a Half-Life game well given that one hasn't been made in over a decade, starting with VR first and then applying the Half-Life IP to it made the process easier than he believes it would have been had they tried to make Half-Life 3 from the start.

https://www.gamesindustry.biz/articl...half-life-alyx