Writing in the comments of his ), Lowrie said issues with motion-capture, among others, are keeping the game back.

"One of the great things about HL2 is that all of the characters that you meet actually look at you when they talk to you no matter where you go or stand. With mo-cap you can#146;t do that, at least not yet," Lowrie said.

"Once you film the actor doing something and capture that motion, that#146;s what the character is going to do," he added. "This works great in movies, but when you make something interactive it gets way less interactive with mo-cap. So that#146;s one of the things they#146;re working on."

Responding to a comment of "HL3 confirmed," Lowrie poured cold water on that notion, saying, "Sorry, I'm afraid that the opposite is true. HL3 is not being worked on at this time as far as I know."

Lowrie added that Valve is "pretty full up" with its existing portfolio of titles that it continues to support, as well as the Steam distribution platform.

"So, I don't want to get people's hopes up," he said. "I have no idea what they're planning for the future. But I did have that conversation with some Valve folks, so I thought you might like to know what they're thinking about."

Last April, Valve boss Gabe Newell said the studio had gone through numerous "" to bring the game to market. He explained that Valve's silence is in the best interest of gamers because elaborating on the game's development "would probably drive people more crazy."

The most recent Half-Life game was 2007's Half-Life 2: Episode Two. That game advances the story of previous entries Half-Life 2 and Half-Life 2: Episode One. A third episode was planned, but has not seen the light of day.

A was recently spotted in a Valve project tracker.