(Duke Nukem 3D Custom Build for Flash! requires Flash Player 10)
(CONTROLS)
MOUSE= AIM/LOOK Around
E or SPACE= FIRE
WASD= MOVE AROUND
Notes
It’s a tech demo with only the beginning part (2 rooms) of the original game. This game doesn’t have a main menu.
Source
http://www.timiscool.net/dukenukem3d.html (via Wayback Machine)