Health Items Restore 100% Life
On the title screen, press X, X, X, X, SQUARE, SQUARE, SQUARE, SQUARE, CIRCLE, CIRCLE, CIRCLE, CIRCLE.

Infinite Arrows
To have an infinite number of arrows, go to the title screen and press these buttons: X, CIRCLE, SQUARE, SQUARE, X, SQUARE, CIRCLE, CIRCLE, X, SQUARE, SQUARE, X.

Stronger opponents
At the title screen, press X, Circle, Square(2), X, Square, Circle(2), X, Circle(2), X.

Weak opponents
At the title screen, press X, Circle(2), Square, X, Square(2), Circle.

Weapon select
Find each Tuku on all levels to unlock an option at the Sage that allows you to use any weapon on any level.

Arenas
Successfully complete all of the challenges in a level to unlock that level's arena.

Extra costumes and art
Successfully complete the arenas by completing all challenges for both time attack and body count to unlock extra costumes and art.