Commander Keen in Goodbye, Galaxy (stylized as Goodbye, Galaxy!) is a two-part episodic side-scrolling platform video game developed by id Software and published by Apogee Software in 1991 for DOS. It consists of the fifth and sixth episodes of the Commander Keen series, though they are numbered as the fourth and fifth, as Commander Keen in Keen Dreams is not part of the main continuity. The game follows the titular Commander Keen, an eight-year-old child genius, as he first journeys through the Shadowlands to rescue the Gnosticenes so they may ask the Oracle how the Shikadi plan to destroy the galaxy, and then through the Shikadi's Armageddon Machine to stop them. The two episodes feature Keen running, jumping, and shooting through various levels while opposed by aliens, robots, and other