Duke Nukem: Manhattan Project
Duke Nukem: Manhattan Project
A secret boss can be found in the third part of the game's eighth and final chapter Orbital Oblivion, though its existence remained widely unknown for seven years following the game's release until footage of how to reach it was uploaded to YouTube in 2009.

In order to access the boss, Spoiler:first collect all Nukes in the game on Hard difficulty to unlock the X-3000, an automatic "lightning gun" that can target all on-screen enemies. Next, replay the third part of Orbital Oblivion collecting all Nukes again, and then make your way to Mech Morphix's giant Duke cyborg. On the second floor housing its moving arm, there is a path in front of it with two large green vials, one of which is knocked over, and can now be used to access the boss. Spoiler:Going down the path will transport Duke to a barren, rocky platform in outer space, with Earth close by in the background and the secret boss floating in front of him, a giant green orb of energy named Wozma, a parody of the superboss Ozma from Final Fantasy IX. Defeating the boss will send Duke back to its entrance in front of the cyborg arm.
Contributed by MehDeletingLater
The main villain of the game, Mech Morphix, was planned to be Dr. Proton from the first Duke Nukem. However, he was planned to appear in Duke Nukem Forever and, unwilling to cause continuity clashes with both games, the developers decided to replace the character.
Contributed by gamemaster1991