Portal: Still Alive features the full award-winning Portal single-player game from Valve plus a new challenge mode.

A unique take on puzzle gameplay by the makers of Half-Life. Portal is unique that changes how players approach, manipulate, and surmise the possibilities in a given environment in a manner similar to how the Gravity Gun changed our approach to how an object may be leveraged in any given situation. Solve physical puzzles and challenges by opening portals to maneuvering objects, and yourself, through space.