Unofficial Valve site Valve Time has published what it purports to be the first concept art from Half Life 2: Episode 3.

The 31 images were sent anonymously to Valve Time, the site says, and supposedly date back to 2008. Read into that what you will.

Valve Time gives its utmost assurances that the images are genuine, however:

"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," reads a post on the Steam forums. "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!"

Personally speaking, I desperately want them to be real - even if they're four years old, they suggest some progress towards the elusive goal of more Half-Life.

They certainly look legit, anyway...