When I heard GlaDOS's voice way back at E3 2010, memories of traps, puzzles, holes in the sky through which I can fly, and turrets flew through my head. So many turrets. But hearing GlaDOS's voice only meant one thing, and that was a sequel on the way. Needless to say, I was pretty excited with the prospect.

The original Portal was a unique title: using a duo of portals that could be attached to certain surfaces, creating a link between them, you had to solve puzzles at the whim of your robot captor, GlaDOS. Though the game started as a simple series of tests, things became complex when the robot started going from pre-programmed responses, to sarcastic jibes, to snide remarks, and then finally to remarks about killing you. There were companion cubes, puzzles, promises of cake, and the eventual destruction of the malevolent AI.

But clearly things did not go as planned.

Portal 2 begins with you waking up in a run-down version of the compound you thought you had escaped, and things quickly get worse. The story, as you make your way through the facility, unfolds in some unexpected ways, revealing information and history about players in this experience that you might not have expected. And all this is done with some of the best writing I've seen in a video game, ever. It helps that the actors now include the very talented Stephen Merchant as the voice of Wheatley, the sidekick-like personality sphere that delivers some of the best lines in the game, and J.K. Simmons (who Spider-Man fans will likely recognize as J. Jonah Jameson from the films).

Seriously though, it can't be overstated how well the writing has been done in this game. Well-written, perfectly delivered, the lines made me laugh many times. They're also a far cry from the meme-inducing jokes which were driven to the ground by others in the first game. Thankfully, there are no references to cake. Zero. Valve has started fresh here, and done much better because of it.

The puzzles in Portal 2 are, at first, more of the same from the first title. Speedy thing goes in, speedy thing comes out, with switches to press and doors to open. From there, the formula quickly changes, adding new elements like laser redirection cubes, bridges made of light that can be directed with portals, special fluids that alter the properties of the surface they're put on, and more. These are all added gradually, to avoid overwhelming the player, and as they start combining, you realize exactly what kind of complex puzzles they can create.

The actual puzzles are a bit of a different breed this time around. Gone are the rapid-fire portal puzzles from the first game, which had you quickly shooting portals as you sailed through the air like an eagle. The ones this time around are more cerebral, forcing you to look at a puzzle, double check how things work, and then feel like a smartypants when you finally figure out how everything comes together.

Personally, I liked the fast puzzles from the first title. In addition to having a moment of breathlessnes at the end of the puzzle, when your brain catches up to all the rapid movement and flying you just accomplished, it delivered a feeling of pride at what you had just accomplished. Plus it was certainly cool to watch.

Still, for those who clamored for more complex puzzles with solutions that you'll actually need to think about, Portal 2 certainly has you covered. I am no master at these titles, but I'm certainly no dunce either, and I found myself perplexed on more than one occasion; pacing back and forth between puzzle elements, trying to deduce the path to the final gate occurred more than once on my first playthrough. They're still enjoyable to solve, don't get me wrong.

There's also a co-operative mode to play through, and I very much suggest that you do. Far from simply having a single-player campaign with two people at once, the co-op mode in Portal 2 involves two robots: Atlas and P-Body (a converted turret and personality sphere, respectively). Each playing as one of these two robots, two people make their way through a series of completely unique challenges, using four portals instead of two.

Co-op requires a completely new way of thinking to get through, as you're no longer just limited to your own portals and abilities. Also, dying is a much more common occurence (you just respawn). It also has a fun player dynamic to get through, as there are often times that you will rely on the other player to get you somewhere safely. There are many times that they will not. These times are always hilarious. Plus, there are gestures to make, and no matter how often someone else may "accidentally" kill me, a high five always feels good at the end of a tough challenge room. And if you're playing on the PS3, with its split-screen co-op, a high five can be delivered in real life too. Or a punch. You know, depending on the situation.

(Always punch.)

Notable for the PS3 is the inclusion of cross-console compatibility. Not only do you get the ability to download a copy of Portal 2 on Steam if you purchase it for the PS3, but cross-platform gameplay, which means being able to play with a person on the PC while you're on the PS3, is totally possible. Which, if I understand correctly, is the first time this has happened on the PS3.

One of my most significant complaints for Portal 2 is...wait for it...the music. As in, there's too much of it. I miss the silent ambience of the original title, where the music coming in was a sign that things were quickly going belly-up, as a heavy rhythm invariably appeared when some really, really, bad things were going to happen to you. Portal 2 is rife with it. Music is everywhere.

Though I'm not referring to the very excellent Exile Vilify by indie band The National, one of the game's defining tracks. Good stuff.

That being my biggest complaint for the title should tell you a lot about my feelings on Portal 2. It's an excellent game. It is clearly a product of people who wanted to do more with the elements from the first title, and succeeded in every way. The world of Portal has expanded, the characters are given more depth, and the story pulls you back and forth in many unexpected ways with a climactic finale that might leave you breathless. Fantastic writing, excellent gameplay, and a level of polish and playtesting so high that you know it's got to be a Valve title, Portal 2 is simply a game that can not be missed.