About: Portal:

"Portal: Still Alive” features the full award-winning “Portal” single-player game from Valve plus a new challenge mode. Designed to change the way players approach, manipulate and surmise the possibilities in any given environment, “Portal” has earned more than 70 industry honors for its innovative gameplay, with more than 30 Game of the Year Awards. Solve physical puzzles and challenges by opening portals to maneuvering objects, and yourself, through space. The game is debuting on Xbox LIVE Arcade in 2008.