Star Trek: 25th Anniversary (a combination of flight simulator and adventure game) was the first critical and popular hit in the Star Trek computer gaming franchise.
Game play was broken down into several "episodes" reminiscent of the Star Trek television series (the game was portrayed as "the lost fourth season").
Much like the away parties of the series, the game put the player in control of as many as four characters at once. The adventure team consisted of the series' main characters, Captain James T. Kirk, Mr. Spock, and Dr. McCoy, and an occasional "red-shirted" security officer, who would be the first to be killed should the player make a fatal misstep. Sulu, Scotty, Uhura, and Chekov would have to wait for the sequel, Star Trek: Judgment Rites, to appear on the away missions.
Space combat involved maneuvering the Enterprise and firing her weapons at enemy starships. In Star Trek: 25th Anniversary the player could assign Scotty to repair the ship's systems (e.g., prop up the shields, restore weapon functionality, or repair the scanners to remove static from the main screen). Throughout the game, there are only a few instances, such as the final battle, where the player must engage in combat.
Destroying the Enterprise or killing one of the main characters would end the game and require the player to restart from the last saved game. This was mandated by Paramount, which had final approval rights on the game's contents
Getting a "red shirt" killed could be accomplished in almost every episode and would not end the game, but would lower the mission score. At the end of each mission, players received a message from Starfleet Command on how well they had done (100% being perfect while less than 50% would be considered a botched mission). It was possible to complete missions but fail every objective, giving an unsatisfying ending. At the end of the game, the player would receive a final evaluation from Starfleet Command. A "Very High" score would result in the crew being granted shore leave, while a sufficiently low score would result in Captain Kirk being demoted, removed from command of the Enterprise, or a similarly bad end.
The original cast of Star Trek provided the voices on the CD version, including William Shatner, Leonard Nimoy, DeForest Kelley, James Doohan, George Takei, Nichelle Nichols, and Walter Koenig. The character Harry Mudd also made a guest appearance in one of the game's episode (though the original actor, Roger C. Carmel, did not voice the role, as he had died in 1986).
The game contained a copy-protection system that asked the player to consult the game's manual to find out what star system to warp to on the navigation map. Warping to the wrong system would send the player into either the Klingon or Romulan neutral zones, and initiate an extremely difficult battle that often ended with the destruction of the Enterprise.