If you thought GLaDOS might go easier on robots than treacherous, squishy humans, you'd be wrong. The two robot stars of Portal 2's cooperative offering--one tall, with an egg-shaped body and orange eye, and one short, with a blue eye in its spherical body--are no better off than the human heroine of the single-player campaign. They face a series of lethal test chamber puzzles in the game's co-op mode, as well as the unhinged snark of Aperture Science's AI overseer.
The test chamber doors are arranged around the Hub, a towering room of platforms and bridges, navigable via the portal guns with which the two bots are equipped, over a pool of nonspecific but lethal goo. ("How can you fail at this?" GLaDOS taunts after a misstep, "It isn't even a test.") Routes to further test chambers open up as you make progress, and you'll be able to access any puzzles you or your co-op partner have already beaten. We sampled the first set of tests, labelled "Team Building"--a series of puzzles to familiarise you with key co-op features and introduce puzzle-solving tricks in their simplest form.
In your co-op toolset is the ping ability, which lets you pinpoint a spot to which you want to draw your buddy's attention--say, a button you need pressed or somewhere you need a portal placed. There's also a picture-in-picture view that lets you see through your partner's eyes--useful for online cooperative play rather than the split-screen two-player mode. Combined with voice chat, these tools should make collaboration easier in the fiddliest puzzles. Less essential, but more adorable, are the gesture abilities, including a simple wave and a celebratory high-five. Unlike GLaDOS, these bots don't talk. Like WALL-E, they are all the more charming for it.
The first few tests keep Blue-bot and Orange-bot in parallel rooms, separated by glass walls, and make the point that cooperation isn't preferable--it's mandatory. In an early test, one robot has to press a button in its room to drop a cube from the ceiling in the other's. Unless the second robot grabs it, the cube falls into another pool of lethal goo and is lost (GLaDOS: "Nice catch, Orange"). In another pair of side-by-side rooms, one robot must fire portals through slots in the dividing wall to let his neighbour pass obstacles on the other side. To differentiate the portals from each robot's portal device--especially since later on in the game all four portals will be in play simultaneously--one produces blue and purple portals, the other red and orange.
As the robots progress together through the tests, finding Portal's familiar cubes and buttons and turret-mounted guns, new items are introduced, too. The prism cube, for instance, must be used to redirect deadly red lasers--"thermal discouragement rays," in Aperture Science's euphemistic techno-corporate speak--towards goals or to destroy those three-legged turrets. It's all too easy to scorch your partner while fumbling with a prism cube, but death is never the end for these two--if destroyed, a bot is reconstructed and tossed back into play. GLaDOS wouldn't want either robot getting out of it that easily. "Oh, sorry," she says, distracted. "I was just thinking of all the ways humans can die--unlike you."
In a more advanced "team building" exercise, the robots are reunited in a single chamber and must cross a river of more deadly liquid to the exit on the far side. The solution begins with an infinite falling loop, with one portal placed directly above another. While one robot falls and falls, the second must hit a button to temporarily retract an obstacle over the river and then quickly relocate the upper portal to send the first flying over the liquid--to hit a switch that builds a bridge that allows the other to cross over. It's a twist on the falling puzzles from the first game, now demanding the intervention of a second player, rather than having the falling player shoot a new portal mid-plummet.
Expect the complexity of the tests to ramp up steadily (the co-op campaign is about twice as long as the original Portal, as is the single-player campaign), with new items introduced along the way; back in the Hub, the second set of test chambers is labelled "Mass and Velocity," and the third is labelled "Hard Light Surfaces." But the learning curve for collaboratively solving puzzles is cleverly done, so that you'll be instinctively looking for opportunities to cooperate. So Aperture Science does know a thing or two about team building. Find your Portal 2 co-op buddy before launch in April.