Have a 5 Octopi rank at the end of the Hong Kong level.

Have a 4 Octopi rank at the end of the Hoover Dam level.

At the extras menu, press Down, Left, Up, Left, Right, Down, Left, Up to unlock all
multi-player mode skins.

Have a 5 Octopi rank at the end of the Volcano Lair level.

Have a 5 Octopi rank at the end of the Hoover Dam level.

Have a 2 Octopi rank at the end of the Hong Kong level.

Use the following trick when you are trying to kill an opponent with a name above their
head. When you spot one of them, go for them before you try to kill anyone else -- they
always have a good gun. .Kill them with a shotgun or strong gun. Pick up their gun, then
go around killing their other teammates.

When your opponent uses his or her shield, hit them with your stun power. They will be
unable to hack out of it because their shield drains all of their power. Then, pick them
up and throw them. When your opponent uses MRI Vision, use your shield. You will become
invisible to them. Try different combinations of weapons to see which works best for your
fighting style.

Have a 2 Octopi rank at the end of the Fort Knox level.

Have a 3 Octopi rank at the end of the Auric Enterprises level.

Have a 2 Octopi rank at the end of the Fort Knox level.

Have a 4 Octopi rank at the end of the Crab Key level.

Have a 5 Octopi rank at the end of the The Octopus level.

You do not need a Harpoon RL to destroy a chopper. Here are some other guns that you can
use: AR4 Commando, HS90 + HS90, HS90 + Jackal, Jackal + Jackal, Mamba + HS90. Never go
against a chopper with an SPEC-9.

Have a 2 Octopi rank at the end of the Crab Key level.

Have a 5 Octopi rank at the end of the Midas Casino level.

At the extras menu, press Down, Right, Down, Right, Down, Up, Down(2), Right, Down, Right,
Down, Up, Down, Left to unlock all artwork.

Have a 3 Octopi rank at the end of the Crab Key level.

When you have a Harpoon and are trying to kill someone else with it, shoot the ground
around their feet. This is much easier then trying to shoot the person's body. You may
even kill more than one. Note: Do not try this with other weapons such as pistols,
machine guns, commandos, etc.

Have a 2 Octopi rank at the end of the Auric Enterpirses level.