x0r_jmp has left a Christmas present for Duke Nukem fans – four builds of Duke Nukem 4Ever from October to November 1996. Here are some screenshots to give you a taste. Unfortunately, we cannot provide a source for the leaked builds, so you will have to do your own searching.
Triaxis:
Seeing the dates made me think this was either a side project or they just started immediately working on a sequel after 3D came out
Another off-note is that a alpha build of Doom 64 (dated October 12, 1996) was also leaked by an unknown user.