If you're struggling with the game then Select the 'Extras' option and go to the 'Cheat' menu and press R2, R1, L1, L2, Left, Down, Right, Up, Square and ALL the cheats at the 'Cheat' menu will be enabled.

Towards the end of the 2nd British Level after you have blown up the fuel depot you will come to two old buildings by the mountain. Go to the building on the left that looks like a church and blow up the door on the right with two grenades. Then throw two more grenades inside the room and a stair case will be revealed when the debris clears. Go down the stair case to find an old man playing a musical instrument that looks like a guitar and a health pack.

When you successfully complete the following campaigns the corresponding FMV Sequence becomes unlocked.

Complete the Russian Campaign:
Unlocks the Making Of 1 FMV sequence.

Complete the British Campaign:
Unlocks the Making Of 2 FMV sequence.

Complete the American Campaign:
Unlocks the Making Of 3 FMV sequence.

Finish the game under the easy difficulty setting to unlock the "Big Head", "Ricochet", "Head Shot", and "Ricochet All" cheat options.

Finish the game under the normal difficulty setting to unlock the "Shink Shot" and "Dead Eye" cheats.

Finish the game under the hard difficulty setting to unlock the "Big 'N' Small" cheat.

Cheat mode:
To unlock 'Ricochet', 'Ricochet All', 'Head Shot'and'Big Head' cheat options successfully complete the game on the Easy difficulty setting.To unlock 'Dead Eye' and the 'Shink Shot' successfully complete the game on Normal difficulty settting and successfully complete the game on Hard setting to unlock the 'Big 'N' Small' cheat

All levels:
At the Level selection screen hold controller two up and with controller one press Start, Select (2), Square.