Press pause during gameplay then hold in L1, L2, R1, and R2 while pressing the following buttons.
Code - Effect
Circle, Right, Circle, Right - All Level 2 Attacks
Triangle, Up, Triangle, Up - All Level 4 Attacks
Square, Left, Square, Left - All Level 6 attacks
X, X, Down, Down - All level 8 attacks
triangle, circle, triangle, circle - All Upgrades
square, square, circle, circle - Always Devastating
X, Down, Down, Down - Boost Experience by 1000
X, down, Triangle, up - Full Arrows/Axes
square, circle, X, triangle - Infinite Missiles
triangle, square, X, circle - Invulnerable
Triangle, Down, X, Up - Refill Your Heath 100%
triangle, circle, X, square - Slo-Mo
triangle, triangle, X, X - Small Enemies
Unlock Secret Missions:
Aragorn: Beat Helms Deep: The Deeping Wall and reach level 10 with Aragorn
Gimli Beat Helms Deep: the Deeping Wall and reach level 10 with Gimli
Legolas Beat Helms Deep: the Deeping Wall and reach level 10 with Legolas.
Play as Isildur:
Beat the secret mission with any character.
Unlock Actor Interviews:
Orlando Bloom Interview: Play as Legolas and reach level 5
John Rhys-Davis Interview: Play with Gimli and reach level 5
Viggo Mortenson Interview: Play as Aragorn and reach level 5.