The portion where he grips the lower side of the gun resembles the magazine assembly of the Dark Star as do the fins on the upper portion of the gun. It may be a concept version or just an artistic variation, but it's still a Dark Star.
"When Chesluk thinks about penguins, he touches himself." -SSJBrohan http://i.imgur.com/uB5U6.jpg
Well, we can call it a Dark Star if you guys want to, but the fore-end of the gun, the most prominent feature in the box art, looks nothing like the version of the Dark Star in the game. Not to mention that the stuff spewing out of the barrel doesn't resemble either the tag or the black hole.
I haven't looked at the concept art, but we should dig out that little book and see if it's in there anywhere.
Dark Star. It says in Conduit wikia, and I have the limited edition which comes with special in game art. They have other versions for the cover (other box art ideas) in it, and in those versions you cans ee clearly that its the dark star.