Duke Nukem 3D: Megaton Edition Message Board  

Since the trainer is retired I found some cheats code for the game, here it is.
dnkroz = god mode
dnstuff = all guns, keys, ammo, everything you need on the map
dnclip = walk through walls

If you have the steam version the cheats don't disable achievements, so you can cheat and get all achievements, the game will not allow you to cheat on the hardest difficulty setting.