A set of concept art purporting to be from Half Life 2: Episode 3 has made its way onto the web.

Somehow procured by unofficial site ValveTime, the 32 images include various new Alyx designs, Gordon Freeman in various bits of cold weather clobber and a few concept pieces showing the Resistance chopper crashed in the Arctic.

The images apparently date way back to 2008, so may not be representative of how the game - if indeed it still exists in any form - looks now.

Are they legit? We've asked Valve for clarification. However, one of the ValveTime team posted the following note on the Steam forums:

"For the avoidance of doubt, I just want to stress that we absolutely would not release these pictures if we didn't know for a fact they were real. They absolutely are.

"Please just enjoy them as they are, and try not to look for conspiracies that aren't there.

"I mean, it's not like we're doing it to attract traffic to our site. We know our server can't cope with the load so we don't want massive influxes of traffic like this. You may have noticed we've been offline since!"