The piece--created by Valve artists Ted Backman, Jeremy Bennett, and Tristan Redford--appears to show Half-Life hero Gordon Freeman within a large Citadel-like environment, a Combine Advisor looming ominously overhead.
IntoThePixel's website labels the art as related to "Half Life EP3," with platforms listed as PC, Xbox 360 and PlayStation 3.
Valve has been mum about the final episode in the trilogy since the release of Episode Two last year. Episode Three will reportedly not be appearing at E3, though Valve will be making an appearance at the event to show off its zombie shooter Left 4 Dead.
Thanks to pixel34 for the tip.