Drew Wolf is an "experienced independent artist/designer" who once worked at Valve. New images posted to their personal website suggest the latter developer could have been working on a four-player fantasy adventure game, "centered around cooperative combat and driven by story".
Named 'Untitled Fantasy Game', Wolf's gallery showcases a batch of "loose sketches" said to be part of an internal R&D project. Here's a sample of the full spread:
"The goal was to present as many groups of four adventures as possible in order to establish a diverse cast of archetypal characters," says Wolf. "After discussion and feedback the group was paired down to ten characters. They would become the projects main characters.
"During the development I created a mood sketch for each character. They were done in a classic sci-fi/fantasy book cover. Each sketch represents a slice of the world each character came from as well as a hint at who they are and what they do. This collateral art helped convey the direction quickly and facilitate creative discussion for each character."
Of course Wolf's words neither confirm or contradict the idea that this untitled, ill-fated game was being worked on by Valve. But, given the artist's past experience (their LinkedIn page suggests Wolf is still employed by Valve), it appears this could be the case.
Check out Wolf's gallery in full over here.