• All weapons and infinite ammo
"All Weapons" and "Unlimited Ammo" cheat Go to the Plant Electrocution 2 level. You will start the Plant Electrocution 2 level by sliding down towards some holes in the ground. The second hole is not fatal. Fall into it and glide (to avoid minor damage). You will see a lit area. Glide down there and pick up the item you find inside. Use the grapnel to exit, jump out of the hole, and finish the slide. The item you picked up should be the key do the door right beside the vines behind the glass. Go inside and fight one of the "Plant Men". You will find an envelope that has a "C" on it in the room. When you finish the game, you can activate this cheat for all weapons and infinite ammunition!

• All FMVs
At the menu screen press the following buttons:
L, L, X, X, Y, X, L, R
You should hear a sound to confirm its correctness.

• Unlock Joker
To unlock Joker, put this password in: JOKER4LIFE

• Envelope D
- In the Gasworks, go two doors down from the start point to find the room where Envelope D is hidden.
- There will be two of Joker's men on the same level as you and two above. Use Batarangs to knock the guns from each one's hands.
- From there, you'll notice a long beam extending to the left toward a sewage pipe. If you look carefully, you will notice a series of boxes floating in the sewage.
- Glide to the first box in the pipe and continue from box to box to reach Envelope D.
- There is no shadow to judge your position and Batman will not grab the edges of these boxes if you miss. Pay close attention to the relative height of each box before you jump because they do bob up and down. If the next box is higher than the one you're on, you'll likely land in the drink
and have to start from scratch.
-According to Nintendo.com, Envelope D will grant you the invisibility cheat after you finish the game.