Opposing Force returns the player to the Black Mesa facility, but tells the tale from the perspective of Col. Adrian Shephard, one of the soldiers sent to clean up the scientists and their reality-altering mess. Just as in Half-Life, things quickly go badly for Colonel Shephard and his men. Ambushed by aliens, Adrian must fight his way through the ruins of the facility in an attempt to reach a helicopter extraction point. What makes Opposing Force shine is the way it expands on the story of Half-Life. Colonel Shephard passes though areas that players of Half-Life are sure to recognize, and he occasionally runs into characters from the original game, including the infuriating Man in Suit. Opposing Force also introduces several new weapons, such as a sniper rifle (with scope), heavy machine gun, and a .357 Magnum with a laser sight. There's even a "weapon" that is actually a common alien creature from the first game; its unique features allow it to be used as a kind of grappling hook. Several new aliens make an appearance as well, almost all of them deadly. They exhibit the same sophisticated AI (artificial intelligence) as the monsters in Half-Life, relentlessly and intelligently attacking Adrian as he makes his way through the game's impressive levels. Fortunately, Colonel Shephard's rank allows him to take command of any soldiers he encounters. Riflemen and machine gunners can be ordered to follow Adrian and provide covering fire, or assigned to guard a door or room. Engineers can cut through locked or blocked doorways, while Medics can heal the injured. Unlike Half-Life's solitary "me against the world" game play, the addition of competent friendly forces provides a feeling of camaraderie: there's nothing like leading a squad of loyal Marines against an alien horde. --Mike Fehlauer