Gradius Collection cheats and cheat codes for Sony PSP

Unlock all weapons and power-ups:
While playing under the easier difficulty level, pause the game, then
press Up, Up, Down, - Down, Left, Right, Left, Right, L, R.

Unlock all weapons and power-ups in the Japanese version of the game:
While playing under the easier difficulty level, pause the game, then
press Up, Up, Down, Down, Left, Right, Left, Right, X, Circle.


Gradius 3:
Unlock Cube Attack: Survive until level 9.
Unlock Gradius level: Intentionally get shot by the Final Boss.
Unlock Salamander level: Intentionally get shot by the Final Boss.
Unlock Stage Select option: Finish the game.
Unlock Extra Mode: Survive until level 9.
Unlock Extra Edit: Finish the game. Select Extra Mode to access more weapons.


Gradius 4:
Unlock Boss Rush mode and Stage select option:
Finish the game once.


Gradius Gaiden:
Unlock Stage select option:
Finish the game on normal or higher difficulty level.