Recently in a Reddit AMA, Valve’s Gabe Newell confirmed that his company is working on unannounced games and that a Half-Life related title isn’t out of the question.
As you would expect, Newell did not speak about Half-Life 3 but he did state that his company is working on at least one “fully-fledged” single-player title. “The number 3 must not be said”, when asked about if Half-Life 3 would ever exist.
“We are continuing to use Source 2 as our primary game development environment. Aside from moving Dota 2 to the engine recently, we are using it as the foundation of some unannounced products”, he said during his AMA. “We would like to have everyone working on games here at Valve to eventually be using the same engine. We also intend to continue to make the Source 2 engine work available to the broad developer community as we go, and to make it available free of charge.”
Out of all this news we can sure to expect Valve will be making a single player game, whether this is related to the Half-Life franchise remains to be seen. Knowing Valve they are very sneaky on things like this when they are ready to reveal their next titles it’ll be when we don’t expect it.