The original Portal had the element of surprise. Its style of first-person physics-based puzzle gameplay was unique. GLaDOS, the murderous robotic villain, was new and vibrant and evil in the most charming way. Cake jokes and songs about surviving dismemberment were still hilarious. It was short, succinct and essential. Creating a sequel without playing all the same notes and making it feel like Portal: The Longer Version is a tough task. For Valve, it's apparently no problem.
From the first moments of waking up in the rusting Aperture Science facility to right before the credits roll, Portal 2 rarely falters. The world is bigger, the story thicker, and the character development more surprising. The mania of GLaDOS, the facility's operator, is molded into unexpected forms alongside a host of brutally funny personalities. The history of the Aperture Science facility is filled in, character origins discussed, and though its pacing suffers as it occasionally strikes a more serious tone, an abundance of cruel jokes and cheerfully sincere death threats prevent it from losing its sarcastic charm. When you're not staring at your screen with wrinkled, pained expression on your face trying to figure out a puzzle, expect to be laughing.
The attention to detail throughout is nothing short of stunning. The facility is in a state of disrepair at the beginning. Once GLaDOS whirs into action, so does the facility, becoming an extension of her body and personality. When you enter a room mechanized crane arms and wall plates spin and shift with an urgency like you walked in on them with their pants down. As Portal 2 progresses, the environments expand from claustrophobic test chambers to yawning underground chasms. Metal girders and structural supports break and crash into each another, snapping apart in chaotic and natural ways, consistently serving not only to entertain the eye but to expand our understanding of the game's characters. The core appeal of something like Portal will never be the visuals, but it's still impressive how much mileage Valve is getting out of its Source technology first used for Half-Life 2 in 2004.
As good as the single-player story is, the co-operative is the real highlight of Portal 2. The beginning of the co-op picks up right after the end of the single-player game, giving you and your partner control of two robots, and serves as a continuation of the story of Aperture Science. It features fewer characters than the single-player mode but is still filled with enough sharp writing, deadpan jokes and absurd humor to keep you entertained between puzzle sections and provide motivation toward an end goal. Better yet, instead of simply recycling puzzle designs from the single-player portion, the inclusion of another player significantly alters the way you need to think.
That's because each of the robotic co-operative characters carries a portal gun, which means two guns and four portals. Valve takes full advantage of the increased capacity for dimensional holes by raising the level of challenge and coordination required. As is obvious if you've ever played Left 4 Dead, Valve knows how a good co-operative mode requires a game design that doesn't simply encourage but requires you to work together. In Portal 2, communication is vital to success.
You can set context-sensitive markers on parts of the environment to wordlessly indicate where a portal should be placed, where a partner should move, and even trigger a countdown clock to synchronize when switches should be hit or buttons pressed. The indicators may feel superfluous at first, but once you're setting up four portal chains of light bridges to block turret fire or redirecting edgeless safety cubes as they fly through open air over bottomless pits, it's obvious how useful they can be. Barely a moment will go by in silence while playing Portal 2 with another, except when you're listening to GLaDOS belittle your intelligence with endearing sarcasm.
Really the only place Portal 2 falters is in the second act of its single-player mode, where the pacing sags and the story becomes more concerned with the past than anything else. Even so, as compared to many other linear first-person games where the stories are little more than shrink wrap and glorify a blood-is-progress philosophy, Portal 2's mid-game doldrums are relatively far more creative and confidently original. Valve's sequel serves as the anti-Call of Duty. Portal 2 is a first-person thrill ride from beginning to end that challenges you to think without failing to entertain.