At nine years old, Half-Life 2 is still regarded as the best first person shooter ever made. The game’s legendary status, meanwhile, has only been enhanced by developer Valve’s reticence about revealing anything at all about a sequel since 2007’s Half-Life 2: Episode 2.

It’s a mystique that makes the screenshots leaked this week even more tantalising. They claim to show a glimpse of Half-Life 2: Episode 4 (we may never know what happened to Episode 3), apparently in development by Arkane Studios, who later went on to produce the wonderful Dishonored.

Here are the screenshots as revealed by fan forum, ValveTime and a short video to go with them. As for Half-Life 3, Valve remains characteristically tight-lipped.