Word was going around that Half-Life 3 would be due for release in late 2014, but now Valve Software officially denied this rumor. Details about the next title in Valve's Half-Life series are slim, the denial of the rumor likely means it's not coming anytime soon. The last title in the series was the episodic Half-Life: Episode 2, which saw its release in 2007.
Since the release of Half-Life 2: Episode 2 in 2007, however, the franchise has gone worryingly quiet and the plot - revolving around the alien invasion unwittingly triggered by the player as Gordon Freeman back in the original Half-Life - left on a cliffhanger ending. Since Half-Life 2: Episode 2, Valve has released a total of eight games - only two of which, Portal and its sequel, arguably take place in the Half-Life universe but which do not continue the storyline of the original series.
Fans, as you might imagine, have been somewhat displeased by the six-year hiatus. Even the most scant of evidence - such as the posting of a supposed Half-Life 3 promotional T-shirt - is taken as evidence that the game is just over the horizon, and some gamers have even held digital sit-in protests in an attempt to get Valve to talk publicly on the subject.