Cheatcodes
Level select - 8ODYS
Invincibility - HPPYHPPY
All weapons - RCKTSRDGLR
Campaign bonus level - WRDRB
Custom 1 gang - TRDDYBRRKS
Brandon Game - NNKNHCKS
Level 1 - FRHBMCTNTK
Level 2 - LHTSPMFRGS
Level 3 - NGLFFPTTFP
Level 4 - SHPPNRVWGB
Level 5 - MRFFCRTKP
Level 6 - LPGCVBBJCF
Level 7 - GLWHJCRNLK
Level 8 - KMKJTMHRNS
Level 9 - FLWWFCWNRK
Level 10 - WSMBCPVRWS
Level 11 - CGJWVRGLNM
Level 12 - KVVLHFHWTB
Level 13 - FCLPJRWTMP
Level 14 - TMFNJMKJGF
Level 15 - PPJLJHRCVV
Level 16 - LNKNSWKGTH
Level 17 - WMNRSMRTR

Floating Gun Buddies:
Enter the extra boat level with the all weapons cheat on. Lay down gun buddies (super-powered or no) anywhere over water. You should now have gun buddies floating closely overhead! Also if you use the super-powered buddies there is a chance a single-barreled floating buddy will appear.

Destroying entrance pods
On various levels you will encounter entrance pods that are either orange or a green. Destroy all the green pods. The orange pods cannot be destroyed. The enemy uses both the orange and green pods.

No damage from Nukes
When a Nuke is deployed, go directly next to it. When it explodes, quickly go to where it detonated. The radiation rings that appear go in a direction away from the Nuke, which leaves you untouched by it.

When a nuke explodes, use a teleporter when the radiation is going to strike you and you will be safe.

Blocking enemies
Place a gun turret that touches the orange front part of a tank barrier to keep enemies from appearing.

Secret Island
On the last level (Aztec), you can go to a secret island. In campaign mode there is a large number of every item on the island. To get there, set off a nuke from anywhere then go to the boat with a wooden bar blocking it. After you set off the nuke you can go right through it. Next, touch the boat and the screen will flash and you may reach the island. If not, just keep touching the boat and you will eventually get there.