Sea Blade Cheats

After pausing the game
press R, Y, L, X, X, R
Pick Mission
After pausing the game
press X, Y, L, X, R, R. Return to gameplay and pick any level

Pause the game and press R, Y, L, X(2), R. Although your health will still decrease, you will not lose a life when it reaches zero.

Enter at menu screen:

R, Y, L, X, X, R Invincibility

X, Y, L, X, R, R Unlock All

While playing, pause and press R, Y, L, X, X, R.

Hit pause during the game, then X, Y, L, X, R, R.