Screenshots from Dishonored developer Arkane Studios' Half-Life 2: Episode 4--or Return to Ravenholm--have surfaced. ValveTime has posted a batch of images it claims are verified and stem from development in 2006 and 2007.
The images show off series-familiar environments and art style. Notably, a HUD element called "Absorption" is present in the screenshots, though it is not clear what this could mean.
This is not the first time Arkane's Half-Life game Return to Ravenholm has been discussed. A year ago, Valve writer Marc Laidlaw told LambdaGeneration that such a project was in development at the studio. He said some ideas were discussed between Valve and Arkane, but ultimately the project was scuttled.