In Iridion 3-D, gamers assume the role of an interstellar prospector returning to earth after the exploration of the distant Orion System. Upon return, it is revealed that the Earth has been invaded by the Iridion Empire, a long-time threat to mankind. Through their journey between Earth and the Iridion Star System, players experience a variety of unique environments including a disposal tunnel of an intergalactic space station and combat over the Pacific Ocean. Each mission encounters an array of vicious mega-robots, bio-mechanic worms, and brigades of Iridion Starfighter combat craft.