It could be the third installment, but no.
Throughout all these years it has been seen as one of the unfulfilled wishes for Half-Life fans it is the fact that Valve, its responsible and creative company, has not been encouraged to launch any continuation of the story, being that the only thing we have seen of all these projects are images and leaks of what could have been, but it was not.
Given this, it should be noted that there are currently rumors about the development of a new Half-Life title, although it is not known if this will be the expected continuation or if, on the contrary, it will be a game that expands its universe, perhaps and as it happened with the Virtual Reality title, alyx. Despite this, as they say, if a company does not do something, a fan may, thereby giving rise to a project made by fans about Half-Life not only having seen the light, but also Valve has approved it Like a game in the series.
Half Life Codename: Loop is a reality that will come to Steam
In this way, it has been seen that Half-Life Codename Loop is the title that a group of fans has made, thus giving rise to Valve having approved the launch of this title on Steam, which is quite a milestone if we take into account that the creators themselves have given the go-ahead to a fan project. In fact, there is very little precedent in the industry.
This information has been confirmed by the developer, Daniel Almenara, also known as PinkyDev, who revealed the great news in a ModDB post detailing that he had asked Valve for permission and warning that a demo would arrive at the end of the yearalthough at the moment it must be said that nothing is known about the launch date.
Therefore, it will be necessary to see how this new project fares, although it remains to be seen if this opens the door for other creators to dare to upload their titles to Steam en masse.