par•a•ble (ˈpær ə bəl) n. a statement or comment that conveys a meaning indirectly by the use of comparison, analogy, or the like
The Stanley Parable is , much as its title suggests, not really a game.
You cannot shoot guns, you do not have recharging shields. You cannot fly, or purchase upgrades.
You can however, think, make choices (regardless of if they matter or not) and experience the uniquely branching and unfolding story.
The creators of Stanley present the game as an experiment in storytelling for video games, and then immediately do everything they can do to not tell you anything about the game it self.
A quote from the devs own summary of the game:
You will make a choice that does not matter
You will follow a story that has no end
You will play a game you cannot win
...it's actually best if you don't know anything about it before you play it :D
And really they could not be more correct with any of those points, and I'm really trying to keep up that tradition.
You play as Stanley, and the story is told to you by a omnipotent narrator (who's voice over is very, very good), after a short cut scene introduction you are led to a series of choices, and that really that.
Many things happen, many things are said by the narrator and you probably will laugh out loud and otherwise be emotionally moved at times, but more importantly the sheer level of thought it provokes is a rare treat for anyone prone to thinking about the natures of things.
Stanley is not very long and probably will only garner you about 2 hours of game play, but several fold that will be spent thinking about it once you've truly experienced everything it has to offer.
Granted not everyone comes into video gaming looking for or wanting something like Stanley, you have to be ready for an interactive story (extremely light on the interaction). I'll say again its not really a game, but it is something that if you are a video game player and are ready to be in a thought provoking story, with a price tag of free (requires Half Life 2, as if anyone doesn't already own that) you shouldn't miss it.