Against the Wall has certainly impressed us. The brainchild of Michael Consoli, Against the Wall tasks players with exploring an infinite vertical surface. Their only tool is a wand that allows them to interact with the massive wall, pulling out blocks so they can scale ever-upwards.
At PAX East, a playable build was available to attendees and now everyone can sample it. Windows and Mac users can snag the demo over on the official site and get to scalin' now.