"This is art," says a male voice through an overhead speaker, referring to a small rectangular frame on the far wall in a cramped shoebox of a room. "When you hear the buzzer, stare at the art," the voice commands. With no exit, you've no option but to comply. A metronome-like ticking is audible through the overhead speakers. "You should now feel mentally reinvigorated. If you suspect staring at art has not provided the required intellectual sustenance, reflect briefly on this classical music." The sound of soothing strings is pumped into the room only to be cut off abruptly by a harsh buzzer. You then return to your bed in the Aperture Science Relaxation Center. When you wake up, the world has changed completely. Such are the opening moments of Portal 2.