the two links mcjob posted for whatever reason have two totally different stories for whatever reason and the second one sounds a lot better.
The top link is from a member of the press who was reading notes off of a white-board early in HL3's development period. A combination of faded memory (from 10 years) and just not getting enough time to read the notes properly is why that story sounds disjointed.
The second link is what the co-writer has posted; it appears to be a summary of what would have been HL3's final story as an in-universe letter from Gordon addressed to the player.