The second GLaDOS was revived and that hauntingly digital voice spoke for the first time, I honestly got the chills.  Portal 2 has been a long time coming, and Valve seemed to do all they could to not disappoint.

The improvements Valve made over the original Portal are evident the second the game begins.  The visuals in the sequel are vastly improved from the first game, mainly because this sequel was worked on from the beginning to be a standalone product, not part of a compilation like the original.  The lush greenery breaking into the ruined test chambers at the beginning of the game are eventually replaced with the rusted remnants of a long-forgotten portion of Aperture Laboratories, and all along the way players are treated to a behind-the-scenes look at the inner workings of the complex.  Portal 2 is truly a visual delight.

The game controls exactly the way fans remember it.  The portal gun still fires two portals, one orange and one blue, but the extra gameplay wrinkles Valve added to the mix only serve to enhance the brain-bending puzzles that impede the player's progress.  The new gels are the most obvious addition, and come in three varieties: Repulsion, Propulsion, and Lunar.  Blue Repulsion gel increases jump height and causes main character Chell to bounce; orange Propulsion gel creates a track on the ground that enhances Chell's speed; white Lunar gel is used to make any surface...um...portal-able.  Along with the gels come Aerial Faith Plates to launch the player through the air, Thermal Discouragement Beams to power machinery, Hard Light Bridges to span gaps and also Excursion Funnels, which act as tractor beams that can be redirected in some cases.

All of the new gameplay elements combine to great effect.  The game is perfectly paced, as well, introducing new mechanics one at a time at first, only to combine everything the player has learned thus far a few rooms ahead, almost like a review of sorts.  By the end of the game, certain rooms utilize most, if not all, of the features listed above, creating impossible-to-explain solutions gamers will try (and fail) to tell their friends about.

Portal 2 may also have the best writing I've ever encountered in a game before.  I have never laughed out loud so many times during the course of a video game before.  The best part about the writing is its consistency across the board.  All three of the major speaking roles are funny at all times, and the amount of one-liners and other great quotes will finally put "The cake is a lie" to rest.  I personally feel that GI should give out an end-of-the-year award for best writing, just so that Portal 2 can win it.

The writing would not have the same effect if it was not for the excellent voice cast, however.  The addition of J.K. Simmons and Stephen Merchant, as Aperture founder Cave Johnson and Wheatley the personality spehere respectively, are absolutely perfect.  Ellen McLain reprises her iconic role as GLaDOS exactly how we all remember it from the original game.  An all-around amazing voice cast.

The cooperative campaign is also ingenious.  Separating it from the single-player game was the best possible decision, as the standalone nature of the mode makes it a must-play rather than an afterthought.  I haven't completed it yet, as I just finished the single-player mode tonight, but I can't wait to get back into it.

So why no perfect score?  The game is still tragically short.  While that is not to say that the game does not feel complete (it does), it's just a die-hard fan not wanting this adventure to be finished yet.  Any fans of the original, or fans of puzzle games in general, owe it to themselves to experience this early Game of the Year contender.  If you haven't bought it yet you have no excuse, you monster.