Look, I'm not gonna mince words here. If you own a PC, you owe it to yourself to play Gravity Bone. I don't want to tell you what it's all about, since the game is so short that even telling you the setup would give you information in the same amount of time that you could just experience it for yourself.
I'll just say that it's one of the coolest things I've played on PC lately, and that I can't wait to play the equally short sequel, Thirty Flights of Loving, that Blendo Games just released on their site and on Steam yesterday.
But seriously. Go download Gravity Bone. It's free. Spend 15 minutes playing it. Enjoy.
Gravity Bone [Blendo Official Site, Click "Gravity Bone" for free download]