This version of the game doesn't have true modding support. There is a Total Conversion port of Duke Nukem 64 for the Eduke32 source port. You should be aware of this, however; Gearbox modified the file "DUKE3D.GRP" (that's the game data file) to work with their executable. As such, many mods might be incompatible in some form or another.
















































(yatta of duke4.net has gog codes for the original duke3d, try emailing him asking for one)