Portal 2

No beating around the bush: Portal 2 lived up to and exceeded my expectations (which were high).  And here's how:

1.  Simple game mechanics explored by every angle imaginable.

The game play is pretty easy to understand: open up a blue portal, open up an orange portal.  Whatever goes in the blue portal comes out the orange portal.  Lasers, weighted cubes, yourself.  Use the portals to get from the entrance of each area to its exit while evading any obstacles designed to cause your demise.

Any time I'd get stuck on a puzzle (it happened a couple dozen times), the solution was nearly always a simple return to the basics: take a step back and open up some portals.

2.  Stupendous writing coupled with excellent voice acting.

The bar for comedic writing was set fairly high in the original Portal, and I'm delighted to say that Portal 2kept up pace incredibly well.  The three "main" characters have excellent interactions with each other and plenty of great monologue opportunities when interacting with the player character.  But in addition to just being hilarious: the writing creates excellent moments of sympathy for the characters.

And the voice work is exactly what it needs to be.  Each character is full defined and encapsulated within their first few lines of dialogue.

3.  Story, story, story - but don't shove it down my throat.

We also get a great look into Aperture Laboratories and its development, but it is fully at the player's own interest to discover it.  There is very little delivered narrative, but plenty to discover, which earns Portal 2 an A+ in creative writing and story delivery.

And that's just the single player campaign.  Once I've got a chance to play co-op I'm sure I'll be continuously wow'd.  Worth a pick up, indeed!  Though the game was somewhat brief (I bested it in about 6 or so hours, total), I'm sure it'll be the kind of game I play again and again...