CheatCodes.com has all the official Gradius III and IV PS2 cheats to unlock everything. If you know of any that we don't have, please let us know.
All published and official codes as of Wednesday June 19, 2013 for Gradius III and IV are shown below.
Pause the game and press Up(2), Down(2), Left, Right, Left, Right, Square, Triangle. Note: This may only be done a limited amount of times.
Pause the game and press Up(2), Down(2), Left, Right, Left, Right, X, Circle. Note: This may only be done a limited amount of times.
Successfully complete the game without using any continues to unlock stage select.
Successfully complete the game to unlock boss rush mode.
Successfully complete or accumulate ten hours of game play in Gradius 3 to unlock an "Extra Edit" option in extra mode. This option allows weapon combinations to be edited. More weapons can be unlocked for editing by completing the game a second time, or by accumulating another ten hours of game play.
Reach stage 10 and let the Boss hit you with a bullet to unlock the first Gradius stage in extra mode.
Reach stage 9 in the game to unlock cube attack in extra mode.
To play first stage of Gradius and Salamander, play Gradius III until you get to the final boss who tried to shoot 3 spread electric balls at you. Don't dodge them, touch the middle ball to wrap into Gradius world or touch the lower one to wrap into Salamander world. Once you've entered one of them you can play them again by going to Extra Mode in you menu and selected the world you desire.
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