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Duke Nukem Forever concept art from 2002
The first picture is a render released by Gearbox in 2011, but shows the assault trooper from the version of DNF predating the 2003 lighting system. This model is present in the leaked version from October 2001.
The other pictures are CannibalEd screenshots, leaked on 4chan in 2018, and show various in-game models from the same iteration.
1) the second CannibalEd screenshot shows a variation of the gunship already shown in the 1999 Stratosfear screenshot, but as a helicopter, rather than a futuristic aircraft.
2) the last screenshot shows Bombshell as she appeared in the Quake2 iteration. The texture is still present in the leak, but the model is gone.