I'm not really quite sure what to say about The Stanley Parable. The game is touted as an experimental, narrative-driven interactive fiction. You really have to experience it to understand it. Even then, you probably won't understand it.
Apparently, The Stanley Parable started out as a Source mod two years ago. After it met with a fair amount of popularity, the creator (one Davey Wreden) decided it was time for an HD remake. With the help of Steam Greenlight, the remake lands next week. In the meantime, you can download the brilliant demo (also from Steam) to get a small inkling of what this thing is all about.
Fair warning, though. It's very dry and very British. Which is awesome.