Here are the DN3D cheat codes :


dnkroz - god mode on/off
dncornholio - same as dnkroz
dnstuff - all weapons, full ammo, etc.
dnitems - all inventory items, keycards, etc.
dnscotty## - warp to episode# level#
dncashman - duke throws a bunch of cash every time you use the "open" key or  button
dnview - a change of perspective
dnrate - displays the framerate
dnskill# - change the skill level
dnhyper - ???
dnmonsters - ???
dncosmo - gives you message "register cosmo" or something like that
dnallen - another message, this time about Major Stryker