"Wing Commander: Secret Missions was an add-on campaign from Origin. It requires the WC1 software to run, but adds new missions, new ships, a new storyline, and an increase in difficulty. The game was also released for the Super NES as a stand-alone cartridge.
The Tiger's Claw, on maneuvers in the Goddard System, receives an abortive distress call from Goddard colony. When the Claw arrives, though, nothing is left but wreckage and corpses; a quarter of a million colonists have been killed. Confed realizes that this is the work of a new Kilrathi weapon, the "Graviton weapon," which is able to increase the power of gravity by over a hundred times. Clever work by the Claw's crew and pilots allows them to capture a Kilrathi courier ship, which reveals that this weapon is mounted on an entirely new class of ship; C-in-C codenames it the Sivar-class dreadnought, after the Kilrathi god of war. Bluehair leads the strike against the Sivar and destroys it in the Vigrid system; for unexplained reasons, ships of that class and armament are never seen again.
Unlike the original game, The Secret Missions does not feature a branching mission tree; every player plays the same missions in the same order. However, if the player does not the fulfill the mission requirements at any system, he immediately plays the two losing "retreat" missions that are not on the winning path."
Source: Wikipedia, "Wing_Commander_(video_game)," available under the CC-BY-SA License.