Kotaku’s Stephan Totilo peels back the curtain a smidge:

So starts the next Portal game, this spring’s Portal 2, with dark, dark humor. In the game’s single-player campaign, estimated by a representative from the game’s development studio Valve to run six or eight hours, you are once again in control of Chell. In the first game she was, perhaps fitting with the theme, an empty character. Little in the opening of Portal 2 defines her sharply. She’s you. But she’s not the star. Right away, a robot named Wheatley is.

This is the set-up: You’re in what looks like a hotel room that contains a bed, some small pieces of furniture. You’re being given directions off-screen by a voice that tells you to do things like to look at a painting. “This is art,” you’re told. You are informed that it may relax you. And, if not, here’s some classical music. (Note: humor isn’t usually humor when it’s retold, so I’m sparing you a recital of most of the intro jokes.) You’re supposed to go to sleep, maybe wake up shortly, but instead you’re waking up at some time much later — defined as “9 9 9 9 ….” who-knows-what later by what sounds like a malfunctioning computer. The dent from your body on the room’s bed is about a half-foot deep.

Wheatley barges in. He’s a spherical robot with a blue light for a face and the cheerful British star of Extras, Stephen Merchant, for a voice. He’s little more helpful than GLaDOS was as he tries to help you chin up while exposing you to the fact that your room is both falling apart and one of many suspended in some huge chamber. We’re still in Aperture Science’s massive labs, same place as the first game, but much, much later. Metal is rusted, the place is wrecked, Wheatley’s got our apartment on rails or something and is careening it through Aperture Science. Wheatley is either trying to help Chell or kill her. You can never be sure in a series like this, but he’s telling good jokes.