Duke Nukem: Manhattan Project is a platform game developed by Sunstorm Interactive and published by Arush Entertainment in 2002.
When George Broussard, co-owner of 3D Realms, was interviewed about future projects in 1996, he mentioned a side-scroller called Duke Nukem Forever being in production and supposed to come out in late 1997. However, that project was cancelled and the name Duke Nukem Forever got reassigned to the game that took 15 years of development. After Manhattan Project was first shown to the public, rumours began to spread about it actually being the cancelled Duke Nukem Forever side-scroller. But this wasn’t true and has been clarified, since it’s an original game done by Sunstorm.