Ok... if you go on the level "up-link" (only two players) and you throw a frag grenade at one of the poles by the barrels out side, you might see the pole fall off or see the barrel explode. Have fun doing this.
All multi-player mode skins
At the extras menu, press Down, Left, Up, Left, Right, Down, Left, Up.
Auric Enterprises Art
Have a 2 Octopi rank at the end of the Auric Enterpirses level.
Auric Enterprises Art 2
Have a 5 Octopi rank at the end of the Auric Enterprises level.
Crab Key Art
Have a 2 Octopi rank at the end of the Crab Key level.
Crab Key Art 2
Have a 5 Octopi rank at the end of the Crab Key level.
Easy Ammo
If you are on low ammo, hold A to will drop your weapon. Pick it up and you will have full ammo.
Fort Knox Art
Have a 2 Octopi rank at the end of the Fort Knox level.
Fort Knox Art 2
Have a 5 Optopi rank at the end of the Fort Knox level.
Hong Kong Art
Have a 2 Octopi rank at the end of the Hong Kong level.
Hong Kong Art 2
Have a 5 Octopi rank at the end of the Hong Kong level.
Hoover Dam Art
Have a 2 Octopi rank at the end of the Hoover Dam level.
Hoover Dam Art 2
Have a 5 Octopi rank at the end of the Hoover Dam level.
Midas Casino Art
Have a 2 Octopi rank at the end of the Midas Casino level.
Midas Casino Art 2
Have a 5 Octopi rank at the end of the Midas Casino level.
Multi-player Adrenaline
Have a 5 Octopi rank at the end of the Hong Kong level.
Multi-player Auric Elite skin
Have a 4 Octopi rank at the end of the Fort Knox level.
Multi-player Bathhouse level
Have a 3 Octopi rank at the end of the Hong Kong level.
Multi-player Carver's Press level
Have a 3 Octopi rank at the end of the Auric Enterprises level.
Multi-player Dr. No Elite skin
Have a 4 Octopi rank at the end of the Auric Enterprises level.
Multi-player Dr. No skin
Have a 4 Octopi rank at the end of the Crab Key level.
Multi-player Dr. No's Reactor level
Have a 3 Octopi rank at the end of the Crab Key level.
Multi-player Eve Overcharge
Have a 5 Octopi rank at the end of the Hoover Dam level.
Multi-player Fissure Platform level
Have a 3 Octopi rank at the end of the The Octopus level.
Multi-player Goldeneye implant
Have a 2 Octopi rank at the end of the Fort Knox level.
Multi-player Goldeneye's Retreat level
Have a 3 Octopi rank at the end of the Volcano Lair level.
Multi-player Lair Elite skin
Have a 4 Octopi rank at the end of the Volcano Lair level.
Multi-player Lair Guard skin
Have a 4 Octopi rank at the end of the The Octopus level.
Multi-player Lethal Strike
Have a 5 Octopi rank at the end of the Auric Enterprises level.
Multi-player Midas Vault level
Have a 3 Octopi rank at the end of the Midas Casino level.
Multi-player Oddjob skin
Have a 4 Octopi rank at the end of the Midas Casino level.
Multi-player Pump Room level:
Have a 3 Octopi rank at the end of the Fort Knox level.
Multi-player random weapons
Have a 5 Optopi rank at the end of the Fort Knox level.
Multi-player Rapid Eye Recharge
Have a 5 Octopi rank at the end of the The Octopus level.
Multi-player Regeneration
Have a 5 Octopi rank at the end of the Midas Casino level.
Multi-player SPEC 9 side-arm
Have a 2 Octopi rank at the end of the Fort Knox level.
Multi-player Speed Loader
Have a 5 Octopi rank at the end of the Crab Key level.
Multi-player Triad Informant skin
Have a 4 Octopi rank at the end of the Hong Kong level.
Multi-player Turbine level
Have a 3 Octopi rank at the end of the Hoover Dam level.
Multi-player Turbo
Have a 5 Octopi rank at the end of the Volcano Lair level.
Multi-player Xenia Onatopp skin
Have a 4 Octopi rank at the end of the Hoover Dam level.
Octopus Art
Have a 2 Octopi rank at the end of the The Octopus level.
Octopus Art 2
Have a 5 Octopi rank at the end of the The Octopus level.
One Life Mode
Successfully complete the game under the hard difficulty setting.
Paintball mode
At the extras menu, press Right, Left, Right, Left, Down, Down, Up, Up.
Unlock Everything
Enter the following at the main menu: Right, Left, Left, Right, Left, Left, Right, X, Y, Y, X, Right, Left, Z.
Volcano Lair Art
Have a 2 Octopi rank at the end of the Volcano Lair level.
Volcano Lair Art 2
Have a 5 Octopi rank at the end of the Volcano Lair level.