Portal

Portal is a new single player game from Valve, creators of Half-Life 2 and Counter-Strike. Set in the mysterious Aperture Science Laboratories, Portal has earned over 15 Game of the Year Awards and offers gamers hours of unique gameplay. The game is designed to change the way players approach, manipulate and surmise the possibilities in a given environment; similar to how Half-Life 2's Gravity Gun innovated new ways to leverage an object in any given situation. Players must solve physical puzzles and challenges by opening portals to maneuvering objects, and themselves, through space.