It looks like Half-Life 3 might never happen after all. If it does, it will be without one of the its key developers. Since 1997 Marc Laidlaw has been working as a writer at Valve. Laidlaw was the sole writer for both Half-Life and it's sequel. After that, Valve appointed him as the lead writer on Half-Life Episode 1 and 2.
Unfortunately, Laidlaw is no longer with Valve; he has retired.
"I am no longer a full or part time Valve employee," wrote Laidlaw to a fan. "No longer involved in day-to-day decisions or operations, no longer a spokesperson for the company, no longer privy to most types of confidential information, no longer working on Valve games in any capacity,"
Why did the Half-Life writer leave Valve? Apparently, it's because he feels 'old' and would rather go back to work on his own projects than on projects that require a bunch of people.
"An outwardly obvious reason is that I'm old, or anyway oldish," explained Laidlaw. "My nickname when I first started at Valve in 1997 was 'old man Laidlaw'. The little baby level designer who gave me that that nickname is now older than I was then.I had a good run but lately I have been feeling a need for a break from the collaborative chaos of game production, and a return to more self-directed writing projects."
Laidlaw isn't entirely writing Valve and Half-Life off of his list though. The writer expressed that Valve can consult him "if questions come up that I can help them answer." However, he does acknowledge that where Valve takes Half-Life from here isn't up to him.
"Where Valve may choose to take Half-Life in the future is not in my hands," Laidlaw said.