Like Natural Selection, Garry's Mod and Dear Esther before it, the experimental narrative, or perhaps narration, driven Half-Life 2 mod the Stanley Parable is going stand alone. A slightly sinister teaser video (ironically not available in HD) promises a new surprise in the HD version.
According to the official site the game will be released "some time in 2012 for Windows and hopefully OSX" and a mobile version will also be coming out on iOS.
If you're impatient it out you can download the original mod from ModDB.
Update: The game's creator has stated on Reddit that he thinks the game will be twice as long as the original mod.