Tom Francis, creator of Gunpoint, is letting certain people alpha test his upcoming game, Heat Signature. Anyone who owns the "Exclusive Edition" of Gunpoint on Steam has access to the new game until August 30. While Mr. Francis says it's not worth it to buy into this just for a rough alpha, I'd argue that if you don't own Gunpoint by now, what are you doing with your life?
After playing around with Signature, I can definitely recommend checking it out. It's a bit rough around the edges, but the concept of flying around space all sneaky-like and hijacking other ships is a blast. So go check your Steam library! And if you don't own Gunpoint, go buy it!