Installation Instructions for the Duke!Zone 2 Demo. 1. Unzip the included files into your Duke Nukem 3D directory. 2. While in the Duke Nukem 3D directory type D!Z2DEMO. 3. Type 'E' to play easy version or 'H' to play the harder version. Duke Nukem 3D should then begin and you should be ready to jump roof-top to roof-top, splattering aliens along the way!