After giving fans a few days to get to grips with the news, the company has now shared even more details about the project, explaining the game will be a "full-length virtual reality entry" in the series.
Slated for launch on Steam in March 2020, the title will be compatible with "all PC-based VR headsets" on day one, which seems like a sensible move designed to get the game into as many hands as possible.
However, owners of Valve's own VR headset, the Valve Index, will be able to pick the game up for free while all other VR owners are stuck with the $60 price tag.
"Set between the events of Half-Life and Half-Life 2, Alyx Vance and her father Eli secretly mount the resistance to the brutal occupation of Earth by a mysterious alien race known as The Combine. As Alyx, players take the fight to the Combine to save the future of humanity," explains a press release.
"Half-Life: Alyx was designed from the ground up for Virtual Reality and features all of the hallmarks of a classic Half-Life game: world exploration, puzzle solving, visceral combat, and an intricately woven story that connects it all with the characters iconic to the Half-Life universe."
While the project has quite rightly made headlines for being the first new entry in the series in around 12 years, it's also a notable return to game development for Valve, which has slowed down first-party production in recent times.
Speaking about that return to the trenches, Valve founder Gabe Newell explained the prospect of working on an ambitious VR project reinvigorated the company.
"VR has energized us. We’ve invested a lot of ourselves in the technology. But we're also game developers at heart, and to be devoting ourselves to a VR game this ambitious is just as exciting," he commented. "For that to come in the form of Half-Life feels like the culmination of a lot things we care a lot about: truly great games, cutting edge technology, and open platforms. We can’t wait for people to experience this."
Valve also plans to launch a set of Source 2 tools, including an update to its level authoring tool Hammer, alongside Half-Life: Alyx in March 2020.