Valve has again brought never-before-seen (correction: once-before-seen) footage of Portal 2 to PAX, but this year, it's not focusing on the co-op mode, which it has heavily promoted on account of it being "brand new." To our delight, Valve instead showed us roughly five or six minutes of the game's opening, and introduced a new character - Aperture Science founder and president Cave Johnson, who is voiced by actor J.K. Simmons.
Update: Shaky-cam footage of the demo
When the footage opens, Chell is awoken from stasis in a relatively-fresh-looking room, and Johnson's voice runs her through a brief series of tutorial check-ups (gymnastics test: look up, look down). She's then instructed to return to bed, but when she awakes again, her room is a mess of decay. Wheatly, the personality core which looks after the lab's test subjects, arrives chattering away on a ceiling-mounted track to save her. We learn that an unspecific, but long, amount of time has passed, that a catastrophic power outage is imminent, and that Wheatly is making a last ditch effort to keep every test subject from becoming a vegetable.
To ensure that Chell is without "a very minor case of serious brain damage," Wheatly runs her through a few more tests, which include speaking. Chell, of course, responds to only by jumping, but in his rush Wheatly dismisses her non-response. Valve writer Erik Wolpaw was on hand to explain that the developers wanted Wheatly to be a continuously chattering character, so whenever the player is idle, he'll babble on unendingly (which he definitely did, inspiring rounds of audience laughter).
To free Chell, Wheatly manually controls her room, which is apparently connected to a track system which allows Aperture to deposit subjects around the facility. As he swings her around, bits of the room are torn off, revealing a much larger laboratory than suggested by the first game's test chambers. He eventually manages to break her into what appears to be the facility's original lobby by "manually" opening a docking station (which he discovered to not be a docking station at all). The steel frame of Chell's chamber smashes through the exterior wall, and Wheatly, who is afraid that the "management" will return to see the mess he's in, explains that she's in search of a 'device' which can help them.
Once inside, we see the decaying remains of a once-great facility and the beginning of Portal 2's campaign, which we're told is about two and a half times longer than Portal's (and the co-op section is apparently twice as long as Portal's campaign!).
After the opening video, Valve played footage of a few of the game's puzzles, including one involving repulsion gel, which bounces Chell into the air. According to Aperture president Cave Johnson, whose pre-recorded voice instructs (or, did at one time) the test subjects, we're lucky to be getting the real thing - the first guy got blue paint and broke every bone in his legs.
On the next page: Joshua Weier talks to us about Portal 2's inception...