There has been some discussion about whether or not Portal 2 was "necessary." Its predecessor was a damn-near-flawless gem of a puzzle game, and a big part of its not-inconsiderable charm was its brevity and focus. Portal's core concept was simple—players were tasked with overcoming obstacles by using a gun that opened teleport-holes in walls and floors—but its design was remarkably tight and it featured one of the most hilarious and memorable videogame antagonists of the last decade. Even for a studio with a track record as spotless as Valve's, elaboration upon such a delicate formula could easily lead to overindulgence.
That is to say, the game is entirely linear. Okay, that's a bit of an oversimplification—when players first walk into a room, the puzzle doesn't actually look like that. It looks a little more like this:
But then, what does it even mean for a game to be necessary? Let there be no doubt, Portal 2 is a superbly crafted, joyous experience, a loving tribute to creative design, problem solving, and the remarkable flexibility of the human mind. Its puzzles are clever and for the most part immaculately constructed, and Erik Wolpaw, Jay Pinkerton and Chet Faliszek's script earns the game a place alongside the very funniest of all time. I'd say that by any possible metric, Portal 2 was absolutely necessary.
The word "necessary" is, of course, a bit loaded. Unlike a certain robot in Portal 2, we humans are not actually addicted to the pleasurable bursts of dopamine granted by solving a tricky puzzle. But by the end of the ten or so hours it took me to work through the single-player campaign, I might as well have been. One minute I'd be standing still, looking from wall to wall while scratching my head, and then… something would click. Moments later I would be soaring through the air towards my next goal, grinning like an idiot while feeling smarter than hell.
The goal of many current-generation games seems to be to minimize the distance between the player and the world as much as possible, to erase the hand of the maker and fool us into believing that we are actually experiencing the events on the screen. But Portal 2's beautiful puzzle design exists in plain sight, just beneath the surface. Throughout my time with the game, I was constantly and happily aware that I was progressing through a series of man-made obstacle courses.
In fact, my joy at solving a puzzle was often accompanied by an admiring nod to the men and women at Valve who engineered it. What's more, the presence of a deep and insightful developer commentary track makes a second playthrough of the single-player campaign worth embarking upon, and is further evidence of Valve's commitment to articulate, clear-eyed game design.
"But how does the game play?" you may be asking. Well, it's a little bit hard to describe the actual flow of Portal 2, so I picked up my camera and put together some (highly scientific) visual aids.
The first thing to realize is that when broken down to its mechanical fundamentals, each puzzle in Portal 2 looks more or less like this.