Hard mode
At the title screen, press L1, R1, L2, R2, Square, X, Triangle, Circle.

Easy mode
At the "Press Start Button" screen, hold Up/Right + X + Square, then press Start. Now enemy attack and defense power will be reduced by half, and more time will be available to complete each level.

Flight mode
Beat the game in less than 1:30:00. Then, hold L2 + R2 and press X on controller two. Now while playing a game, press R2 on controller one to climb, and L2 to dive.

Control map movement
Pause the game and enter the "Map" option. Then, press Select to stop the map movement. Now press L1, L2, R1, R2, and the D-pad to move around the map.

Level skip
Load a saved game and repeatedly tap Start until the save game message appears. Then, choose "No" to continue a game at the next level.

Extra options
Use a memory card and beat the game in less than 1:30:00. Then after the title screen appears again, press Start. Now choose the "Special" selection on the screen to access level selection, view FMV sequences, enter sound test mode, and other options.

Reset game
While playing a game, press L1 + L2 + R1 + R2 + Select.