Thought it took over a decade after Half-Life 2: Episode 2 for the next entry in the franchise, Half-Life: Alyx to be released, many of the developers on the project feel emboldened by Alyx's reception to continue the series sooner rather than later.
This comes from Half-Life: Alyx - Final Hours, a fifteen-chapter article in the form of an app available now on Steam, in which Geoff Keighley provides an in-depth look at the development of the game itself, the Half-Life franchise more broadly, and VR at Valve since the release of Half-Life 2: Episode 2.
In addition to the breakdown of Alyx's development, Keighley shares other details about the franchise since 2007, including that Alyx marked at least the sixth attempt to do something with the property since Half-Life 2: Episode 2.
The gradual quietening from Valve on new software releases over the last decade, Keighley writes, was due to a mix of a focus on development on internal software engine Source 2 (which eventually was realized in Dota 2 and subsequent titles) and an internal culture that promoted ease of starting new projects -- meaning for years there were numerous internal software projects that were begun, but never finished.