Mark Laidlaw, the man who wrote Half Life, Half Life 2 and was the lead writer for the subsequent two Episodes, posted on his personal blog the entire plot to the mythical Episode 3.
Why he did this or even if this is all true, remains a mystery. But here is a couple of excerpts and I have to say, it is pretty good:
(He changed the names of the characters, probably for legal reasons)
I hope this letter finds you well. I can hear your complaint already, “Gertie Fremont, we have not heard from you in ages!” Well, if you care to hear excuses, I have plenty, the greatest of them being I’ve been in other dimensions and whatnot, unable to reach you by the usual means. This was the case until eighteen months ago, when I experienced a critical change in my circumstances, and was redeposited on these shores. In the time since, I have been able to think occasionally about how best to describe the intervening years, my years of silence. I do first apologize for the wait, and that done, hasten to finally explain (albeit briefly, quickly, and in very little detail) events following those described in my previous letter (referred to herewith as Epistle 2).
To begin with, as you may recall from the closing paragraphs of my previous missive, the death of Elly Vaunt shook us all. The Research & Rebellion team was traumatized, unable to be sure how much of our plan might be compromised, and whether it made any sense to go on at all as we had intended. And yet, once Elly had been buried, we found the strength and courage to regroup. It was the strong belief of her brave son, the feisty Alex Vaunt, that we should continue on as his mother had wished. We had the Antarctic coordinates, transmitted by Elly’s long-time assistant, Dr. Jerry Maas, which we believed to mark the location of the lost luxury liner Hyperborea. Elly had felt strongly that the Hyperborea should be destroyed rather than allow it to fall into the hands of the Disparate. Others on our team disagreed, believing that the Hyperborea might hold the secret to the revolution’s success. Either way, the arguments were moot until we found the vessel. Therefore, immediately after the service for Dr. Vaunt, Alex and I boarded a seaplane and set off for the Antarctic; a much larger support team, mainly militia, was to follow by separate transport
Time grew confused. Looking from the bridge, we could see the drydocks of Tocsin Island at the moment of teleportation, just as the Disparate forces closed in from land, sea and air. At the same time, we could see the Antarctic wastelands, where our friends were fighting to make their way to the protean Hyperborea; and in addition, glimpses of other worlds, somewhere in the future perhaps, or even in the past. Alex grew convinced we were seeing one of the Disparate’s central staging areas for invading other worlds–such as our own. We meanwhile fought a running battle throughout the ship, pursued by Disparate forces. We struggled to understand our stiuation, and to agree on our course of action. Could we alter the course of the Hyperborea? Should we run it aground in the Antarctic, giving our peers the chance to study it? Should we destroy it with all hands aboard, our own included? It was impossible to hold a coherent thought, given the baffling and paradoxical timeloops, which passed through the ship like bubbles. I felt I was going mad, that we all were, confronting myriad versions of ourselves, in that ship that was half ghost-ship, half nightmare funhouse.
To see a writer who had become so frustrated with Valve before he retired that he wrote this entire thing just so people could read his hard work in some form is really disheartening. Why the company never released the third episode is a mystery to me. They said that it was too much pressure or couldn’t find a way to ‘revolutionise’ the FPS genre like the previous games did. That always sounded like bollocks to me. Episode 1 & 2 didn’t exactly revolutionise the genre, yet they still made them. Ah well, there is no point bellyaching!
This is all assuming, of course, that this isn’t a very elaborate prank by a man who was so sick of people asking him about Half Life: Episode 3 that he just wrote some fan fiction to shut them up.
Regardless, it is great to have some sort of closure. Even if it is in less than ideal circumstances.
Source: Mark Laidlaw’s blog