Keen 3 Story
Commander Keen 3: Keen Must Die! chronicles Keen's final showdown with the Grand Intellect on Vorticon VI. Following the thwarting of the Vorticon plot to destroy the Earth in Keen 2, Keen realizes that he must discover the identity of the Grand Intellect and eliminate him.
In order to do that, Keen travels to Vorticon VI. However, Keen finds that, under the Grand Intellect, Vorticon VI is a hostile place. In response to Commander Keen's act of disabling the Vorticon Mothership, the Grand Intellect has issued one simple order to all of Vorticon VI: that Commander Keen must die. Landing on the small island of Vortiville, far from the Castle of the Grand Intellect, Keen must set out across the planet in search of his nemesis. Through it, he encounters numerous Vorticon cities and settlements, many of which bear flags and mysterious portraits bearing the Grand Intellect's name, and all of which are filled with hostile aliens. Later, Keen penetrates the Vorticons' military bases, where the lethal VortiNinjas are trained.