CORRECTION: It's the plot of Half Life 2: Episode 3. People have used both to reffer to the same game so it's confusing

His blog post is down but to give you a quick run down it is written in the manner of Gordon writing a letter to the player detailing the events of the plot.

It is written in code, but it's ver obviously Half Life. A redditor re-wrote the post with the correct names for easy readibility.

Note, this is quite likely not the canon story, as HL3 is quite likely dead in the water and if it ever releases this will not be the story we will see. The game itself was picked up by different teams at several times, but attempts always failed.

He maintains it's a fanfic, however since this was the lead writer of the series who's been working at Valve since '97 and until '15, this is i believe the closest we're going to get to closure and to anything close to a canon ending, at least in the forseeable future.

The story has a great sense of finality and in general, feels very appropriate to the story and where it was heading. The final paragraph is not only an admission that this was meant to be the final episode of the second Half Life series (atthe very least) but some are also interpreting it as Laidlaw venting out frustrations regarding the current state of affairs at Valve.

And here we are. I spoke of my return to this shore. It has been a circuitous path to lands I once knew, and surprising to see how much the terrain has changed. Enough time has passed that few remember me, or what I was saying when last I spoke, or what precisely we hoped to accomplish. At this point, the resistance will have failed or succeeded, no thanks to me. Old friends have been silenced, or fallen by the wayside. I no longer know or recognize most members of the research team, though I believe the spirit of rebellion still persists. I expect you know better than I the appropriate course of action, and I leave you to it. Expect no further correspondence from me regarding these matters; this is my final episode.

Yours in infinite finality, Gordon Freeman, Ph.D

So yeah, this happened.