The co-op mode in Portal 2 gives players twice as many portals, and promises to drive players twice as batty.
The latest episode of GameTrailers TV featured an interview with Portal 2 writer Eric Wolpaw and an exclusive trailer highlighting the game's co-op mode. The trailer is extremely short, but it gives players the basic idea of what they'll be doing in the Portal 2 co-op experience.
The co-op mode in Portal 2 shouldn't really be called a mode because it's an entire set of unique levels with their own storyline that are as lengthy as the single-player game. The basic premise involves the trailer's two player-controlled robot characters that were created by GlaDOS to replace humans, which we all know have proven to be trouble. The issue at hand for GlaDOS is that her tests need some kind of human observer, rather than a robot testing robots, so she puts them through practice tests and then sends them deep into the bowels of Aperture Science to find human relics.
GlaDOS's goal is to somehow make these robots more human by having them derive meaning from these relics, which may be anything from a "World's #1 Dad" mug or an old cartoon. The robots will hopefully be able to pass a human "turing test" afterward.
Wolpaw says that the reason Portal 2's co-op levels are completely different is because "four portals changes everything." More information on the co-op campaign will be available at PAX Prime in a couple of weeks.
Source: GameTrailers TV