Origins: Death puts the Emperor in a foul mood. After having been resurrected into a cloned body, he led a devastating campaign to retake the galaxy from the New Republic. The centerpiece of this campaign was the Galaxy Gun, along with the World Devastators. He's consistent, you got to give him that.
Plausible Non-Draconian Reason To Keep it Around: It can also send aid packages and enormous canisters of educational leaflets.
Designer Gripes: Spent shell casings mucking up million-dollar view. When you think about it, you don't really need a gun to do this -- a hyperdrive-equipped starship with a nav computer and loaded to the hull plates with explosives can be just as effective.
Considerably Less Effective Names: The Cosmic Cannon; Planetary Pistol; Mega-Magnum.
Continuity Headache: The Galaxy Gun is seen to blow up the planet Byss, and then in subsequent stories, Imperial ships decide to flee to Byss... but to be fair, they may have been out of the loop rather than seeking refuge among the rubble.
Achilles Heel: The blast radius of its shell is such that by dropping a target directly in front of the cannon means it'll get caught in its own backfire.
Further Reading: Dark Empire II and Empire's End, from Dark Horse Comics (1995-1996) feature this weapon.
