Cheat List:
While playing, pause the game and press the following:

Unlock all bonuses - R2, DOWN, L2, R1, LEFT, L2, DOWN, L1, TRIANGLE
Unlock entire Dark Chronicle - R1, DOWN, R2, L1, RIGHT, R2, TRIANGLE, DOWN, L1
Restore health - LEFT, RIGHT, LEFT, RIGHT, R1, L1, CIRCLE, TRIANGLE, DOWN
Unlock all slams - RIGHT, DOWN, UP, DOWN, DOWN, R1, TRIANGLE, CIRCLE, DOWN
Gain all meter-ups - LEFT, LEFT, UP, UP, L1, R2, CIRCLE, DOWN, TRIANGLE
Infinite reaver charge - DOWN, DOWN, UP, LEFT, R1, R2, DOWN, TRIANGLE, CIRCLE
Real god mode - UP, DOWN, RIGHT, DOWN, R1, R2, DOWN, TRIANGLE, L1
No texture mode - L1, DOWN, R2, RIGHT, R2, UP, TRIANGLE, L1, DOWN
Toon reaver - UP, DOWN, UP, DOWN, R1, R2, DOWN, CIRCLE, TRIANGLE
Tube reaver - UP, DOWN, LEFT, RIGHT, R2, L2, TRIANGLE, DOWN, CIRCLE
Wireframe graphics - L1, DOWN, L1, UP, R1, L2, L1, DOWN, TRIANGLE

Tube Reaver:
At any time while playing as Kain, pause the game and enter: UP, DOWN, LEFT, RIGHT, R2, L2, TRIANGLE, DOWN, and CIRCLE.
You will exit the pause menu and Kain will utter "Beware the tube!" For the rest of the game, Kain will fight with a cardboard tube instead of the Reaver blade. This code will only work for Kain, not Raziel.

Unlock Bonus Material:
When you beat the game, you unlock everything in the Bonus Material section, as well as all the story cutscenes in the Dark Chronicle. The Bonus Material section comprises a variety of extras, such as voice-over sessions, 3D renders, sketches of enemies, and more. The Dark Chronicle is a complete collection of all of the game's cutscenes, viewable in the order they appeared, giving gamers the story in full without the action.