There are almost no modern first person shooters that don’t owe some part of their legacy or mechanics to the Half-Life series in part or whole. That said, the latest installment of the series has taken too long and has been kept too secret to still be optimistic about it.
Valve made a decision that could’ve changed the way AAA titles were released at the time, deciding to opt out of a full scale game and divide their sequel instead into three smaller, more manageable parts. This would allow, according to Valve at the time, for the release of these three parts in quick succession and not leave gamers waiting for six years as they did for the release of Half-Life 2. That plan didn’t exactly work for them, however, as the first two episodes were released in the first five years after Half-Life 2, with Half-Life 2: Episode 2 being released in 2007. The plan fell apart because that was the last time anything was released on the subject, with the alleged Episode 3 still waiting to be released, developed, or even announced.
Normally, for a company as large as Valve, who has released such titles as Left 4 Dead, Portal, and Counter Strike, to keep a lid on a game in production is par for the course. But over a decade of silence and people start to feel like Duke Nukem all over again. Aside from that fact, there hasn’t just been a silence: it seems like there's a ban from ANYONE at Valve to even mention the words ‘Half-Life’. People are always so excited to talk about CS:GO, but the minute any questions pop up about one of their formative game series, and it’s all quiet on the western front. Generally speaking, this means that not only is the game not going to be released anytime soon, reluctance to even talk about it sort of implies they aren’t working on it at all.
Now, it's possible that they're keeping the work intimately secret, and on a need to know basis. Perhaps they're just quietly working away at giving us the perfect sequel to an incredible series that has been in our lives for over twenty years. It isn't very likely, however, considering Valve’s reluctance to even acknowledge the sequel’s existence. That, as an outside observer, makes it seem like there is little to no chance of it happening.
But here’s hoping that there’s still a chance of getting another chance to help Dr. Freeman grab his trusty crowbar and gravity gun and do some real damage.