Snakes of Avalon is a graphic adventure in which you play Jack, a severe alcoholic hanging out in the Avalon, apparently a dive bar that caters to scum like you. You believe that you overhear plans to commit murder and decide, in your boozy and inept way, to foil them.
The technique of the unreliable narrator is common in fiction, and quite often in noir fiction, but it's something I've never seen used in a graphic adventure before. The results are amazingly surreal, as what you interact with is not necessarily anything remotely like reality, but instead Jack's deranged, alcoholic idea of what's going on. This alcoholic dream-logic meshes curiously with the rigorous logic of the graphic adventure, in which specific uses of inventory items produce concrete effects, but the result is more than a little appealing.
Despite the noir elements, Snakes of Avalon is quite funny, reminiscent of games like Time Gentlemen, Please -- certainly more grotesque than a Lucasarts adventure, but sharing something in terms of tone.
It's fairly short, and the puzzles are by no means easy (or even coherent, as your character is not); there is a walkthrough though, should you become stuck. The music by Thomas Regin is excellent; while the game itself has no voice acting, the cut scenes do, and they're pretty good, really.