Go to Settings > System and toggle Enable Cheats .
This method is intended for users with a physical PSP console that has been modified with Custom Firmware (such as PRO-C or ME).
However, the game is notoriously difficult. The PSP’s analog nub is less precise than a console controller, and enemy AI can be unforgiving. For many players, the only way to enjoy the gripping story of Sam Fisher’s past without throwing their handheld against a wall is through cheat codes.