Unlock Battle Arena
To Unlock Battle Arena, earn all the Grades, Then you should get the Master Grade. The Battle Arena Will be open at Robot Beach.
Various Codes
While playing, press START and enter any of these codes:
Sword Upgrade - Hold L1 + R1, CIRCLE, SQUARE, CIRCLE, TRIANGLE, TRIANGLE, SQUARE, CIRCLE, SQUARE.
Complete Current Mission - Hold R1, SQUARE, SQUARE, SQUARE, CIRCLE, Release R1, Hold L1, TRIANGLE, TRIANGLE, Release L1, Hold R1, SQUARE, SQUARE.
Big Heads - Hold R1, TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE, Release R1, Hold L1, TRIANGLE, TRIANGLE, Hold R1 + L1, TRIANGLE, CIRCLE, TRIANGLE.
Mow Grass
Where there are grass, flowers, mushrooms, other foliage, objects other than crates and barrels, and certain decorative objects, you can cut them down to earn a few extra points towards your main score. This is useful in the certain levels that require a high score to earn the grade.
Xpower-ups
Whenever you kill an enemy in a rapid succession, the number to the right of the health bar increases by one up to 10. This represents what points you receive for killing an enemy, multiplied by the number displayed. This is useful in certain missions where a high score is required to earn the grade.