Duke Nukem: Manhattan Project
Duke Nukem: Manhattan Project is a side-scrolling shooter developed by ARUSH Games and released in 2002 by Apogee Software.
Manhattan Project is not a direct sequel to the earlier Duke games, but a side-story: the game features Duke Nukem, this time fighting Mech Morphix, a mad scientist who is using the radioactive GLOPP slime to mutate creatures into deadly enemies, and in the process take over Manhattan island, New York City. These enemies include alligators, Fem-Mechs (female android mutants), and the Pig-cops from Duke Nukem 3D.
It was originally to be called "Nuking New York", feature 12 episodes sold through the Arush site and be set in more recognizable parts of New York City, but this was changed after 9/11. The enemy Duke had to fight was supposed to be his arch-nemesis Doctor Proton, but this changed to Mech Morphix to avoid possible continuity clashes with Duke Nukem Forever.
The game is a side-scroller, but it is built around a 3D engine (Prism3D): levels and characters are fully 3D and both the camera and the main character can also move along the Z-axis (although the paths are fixed), giving it more depth than the usual side-scrollers.
In 1996, George Broussard was interviewed about the next 3DRealms projects: he said that a Duke Nukem sidescroller called "Duke Nukem Forever" was in production and was supposed to come out by Christmas 1997. Later, the project was cancelled and the name Duke Nukem Forever was assigned to the real sequel to Duke Nukem 3D. When Manhattan Project was first shown to the public, rumors started to spread about it actually being the cancelled Duke Nukem Forever sidescroller, but this has since been denied: Manhattan Project is an original game.
Manhattan Project includes a level editor (PrismEd) in the CD, but making new levels for the game never actually became popular, and only a tiny level editing community is currently active.