Portal is a new single player game from Valve. The game is designed to change the way players approach, manipulate, and surmise the possibilities in a given environment: players must solve physical puzzles and challenges by opening portals to maneuvering objects, and themselves, through space.

Portal is a new single player game from Valve. The game is designed to change the way players approach, manipulate, and surmise the possibilities in a given environment: players must solve physical puzzles and challenges by opening portals to maneuvering objects, and themselves, through space.