The Stanley Parable is a remake of the fantastic 2011 Half-Life 2 mod about a man named Stanley. The creators, Galactic Cafe, really don't like sharing anything from the game, as you can see in their trailers, so now they've gone even further and created a standalone demo showing off the behind-the-scenes of remaking their game. You can download the demo now on Steam, and get the full game next week, on October 17th.
The demo is a different version of one they showed at PAX Prime this year, minus a bunch of event-specific references that made it even better and are now forever lost to time. Sadness for those of us that didn't get to attend.
Note: The end of the demo says you can pre-order the game now, but unfortunately that changed between the creation of the demo and its release, so just set a note in your calendar!