Duke Nukem 3D
To gain all the key cards and other items, pause the game, then
press A, C, D, C and press the lower right corner of the screen
While playing, pause the game then press B, A, D, A, D, D for all
weapons and maximum ammo.
Key Card Tip:
When you pick up a key card, you have access to all locked doors.
But if you decide not to use the key card in the level you first
found it in, you may keep it and use it in a later level that you
can't seem to find a key card in. Don't forget! When you start a
new episode, you lose all key cards you may have previously
As you turn a corner, hold down the A button to get a quick shot or
two before your enemy does.