This is a hard game to review, because if I say too much about it, I'll spoil what makes the game good - experimenting, choice and lack thereof. I'll try my best to give a brief outline without spoiling anything.
In the game you play as Stanley, and office worker who realises one day that everyone is gone and the entire office is empty. There is an ever-present narrator which talks over just about every aspect of the game and therein lies the element of choice. For example, the narrator might mention that when Stanley comes to a set of two open doors, he takes the door on his left, but the player has the choice to disobey the narrator if they so wish.
Now, I won't go any further because I've already spoiled too much. This game is absolutely hilarious, I literally laughed out loud while playing.
Now, the downside (there's always one, isn't there?) is the price. To fully finish every avenue the game offers should take the average gamer around 4 hours. That's how much play time I got out of it, anyway, having paid £7.99 for it on Steam (the game has since gone up to £9.99 because the initial price was a two week launch sale). Does that seem worth it? Perhaps not, but let me put it this way...
The fun factor of this thing is extremely high, I got a lot of enjoyment out of it and if you play it with another person like I did, they'll get a similar level of enjoyment out of it too. You could go to the cinema and pay to watch a comedy film, and that would cost you roughly the same price if not higher than this game costs, so I don't really think the ratio is all that bad when you consider the sheer fun factor.
Anyway, The Stanley Parable is available on Steam right now, and there's also a playable demo so that you can see if the game's quirky narrative style is your cup of tea (it certainly is mine!). CLICK HERE to go to the game's Steam store page and check it out!