She is still rattling around inside the Aperture Science lab, but the pristine interiors of the first game are now debris-strewn and cracked after the fall of GLaDOS, the deranged and unstable lab keeper.
While the player is soon reintroduced to the monotone ramblings of GLaDOS, it is the arrival of spherical, one-eyed robot Wheatley which sparks the game to life.
Presented through the first-person shooter engine, (15) viewpoint and controls of Valve's first- person shooter Half-Life 2 (2004), Portal is made up of a series of three-dimensional puzzles that must be solved using a device that connects two points in space, the "Aperture Science Handheld Portal Device 04." The player assumes the role of a test subject in a laboratory, charged with testing the portal device by an artificial intelligence, GLaDOS. The only objective, for the most part of the game, is to traverse a series of puzzle rooms that predominantly require an understanding of the portal device's effect on space.
At the narrative level, the game asks the player to be reliant on a fictional hardware/software system, the supercomputer GLaDOS, as they are reliant on their own hardware/software at home in order to play the game.