I tried to load it on my Vista, it runs OK there. Any suggestions.
GOG's installers are only designed for XP and newer. What you need to do is install the game on your Vista system and then copy the installed files to your 98 system. Once there run the DOS executables directly (do not
use DOSBox). Depending on your configuration you may need to restart into DOS mode in order to play.
EDIT: for reference, DN3D installs to C:\Program Files\GOG.com\Duke Nukem 3D by default.
Thank You I will try to copy the game over.
You can't run GOG- wrapped games on Windows 98. They are made the way they are in order to run SPECIFICALLY on Windows XP/Vista and soon 7.
You are mistaken; in many cases GOG does not need to work much magic beyond removing copy protection (if any) so games may well still work on older versions of Windows even if the installers do not. For DOS games no work is required at all because the games are running in DOSBox rather than natively; DOSBox is able to run original, unmodified DOS software just fine.