CheatCodes.com has all the official Underground CD Vol. 1-3 PSX 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 Saturday May 18, 2013 for Underground CD Vol. 1-3 are shown below.
At the main menu of Disc 2, press Start.
At the "Code Archive" screen of Disc 2, hold Square + Circle and press Triangle (2).
At the main menu of Disc 2, press Triangle, Circle, Triangle(2), Square.
At the main menu of Disc 2, press L1 + L2 + R1 + R2.
At the main menu of Disc 2, press Circle, Triangle, Square, Circle.
At the main menu of Disc 2, press Triangle, Circle, Triangle, Circle.
At the "Event Center" screen of Disc 1, press Triangle, Circle, Square.
At the "Vault" screen of Disc 1, press Square, Triangle, Circle Square.
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