Sometimes in the entertainment world, we don't receive all the answers we want. Take the '80s flick "The Last Starfighter"; geeks of that generation have waited for a sequel to that film for decades. The same can be said for the Half-Life franchise, a hugely popular game franchise from Valve and from all indications, the company simply walked away from it. The last installment in the Half-Life universe was Half-Life 2 Episode 2. We had been promised a follow-up Episode 3 that should have published around Christmas a decade ago.
Christmas 2007 came and went with no new Half-Life Episode and no word on why Valve left us all hanging. Marc Laidlaw, the sole writer responsible for both Half-Life and Half-Life 2, no longer works at Valve but has used his time off to give fans of the series some hope in a world devoid of new Half-Life news. He has taken a bit of pity on gamers and published what seems to be an outline for Episode 3 on his personal blog after all these years.
Laidlaw has changed up a few of the names, presumably to protect himself for Valve's legal team. Honestly it has been so long since I've played Half-Life that other that than Gordon Freeman, I don't remember any of the characters. Laidlaw alone wrote Episodes 1 and 2, and the draft of Episode 3, which takes the form of a letter from Freeman to another character in the game was published to Laidlaw's personal blog.
The crush of fans wanting to read the letter/outline initially brought the server hosting the letter to it's knees, but it appears to be fully operational now. There have been some rumors floating around that suggest Valve might be working on a new Half-Life 3, but so far there has been no firm confirmation of the game. In December of 2015, hints of Half-Life 3 surfaced in the Steam database, but nothing else was seen or heard. In September of 2016, producer J.J. Abrams said that movies in the Half-Life and Portal universes were still a possibility.