Half Life has a fanbase and level of consistent critical acclaim that would have most games companies can only dream of.

The franchise began in 1998 with Valvle's original Half Life, a PC shooter which was also ported to the Playstation. The sequel Half Life 2 landed in 2004 after a protracted development phase. It was followed by a couple of add-on packs – Episode One and Episode Two. An anticipated third instalment, rumoured to be set in the Antarctic, never materialises.

The huge popularity of all titles – and since the games industry is hardly shy of producing sequels, certainly when games have been as uber-successful as this – has meant speculation is rife as to a sequel. Though no official word has come from Valve as yet, there have been some rumblings…

Half Life 3: Rumours

Valve head-honcho Gabe Newell has confirmed in an interview in mid-November 2012 that the firm is working on a new game engine

Speaking to assembled questioners from 4chan.org, who had gathered to wish him a happy 50th birthday, Newell said: "We've been working on new engine stuff for a while," before adding: "We're just waiting for a game to roll it out with".

Unfortunately, he didn't go so far as to name Half-Life 3, but it certainly got everyone thinking about it.

At Gamescom in August 2012, T3 discovered what looked like evidence of it’s existence – when Half Life 3 was listed in a PDF from the games show's website, which lists all the titles that will be announced at the conference.

Alas no announcement appeared, however it did serve to spark further speculation that the title is at some stage of the production process, even if Valve hadn’t announced as such.

Half Life 3: Open World

One of the strongest rumours to date pointing to it’s existence sprang from a French games site, which claims an anonymous source confirmed that not only is Half Life 3 in development, but it will have some RPG elements, and even been more of an open world affair akin to Skyrim. 

According to the same source, the game has had something of a stop-and-start development history so far, with the focus shifting a number of times.

Half Life 3: Release Date

The same French source mentions ‘after 2013’ as a realistic launch date. This certainly seems likely, considering there has been no preliminary announcement as yet. 

Half life 3: Screenshots

Back in June, a number of what might be concept imagery for Half Life 3 emerged from another anonymous source. While it’s possible they are leftover scraps from previous games, it has been pointed out that certain details imply a post Half life: Episode 2 story line. 

Below are a couple of select pics from the Valve Time Facebook page, which you can view in full here.

Half life 3: Trailer

Nothing official has emerged yet, however there is a wealth of fan art that has cropped up alluding to either Half Life 2: Episode 3 or Half Life 3 – as well as a number of trailers of a some particularly keen followers of the franchise have put together – such as this:

We will of course bring you all the official images and videos as they break.