CheatCodes.com has all the official Sonata 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 Friday May 24, 2013 for Sonata are shown below.
At the title screen, press Triangle on controller two, then begin a game to start in the past. Press R1 on controller two to advance to the present, or R2 on controller two to advance to the future.
Found some tricks that we don't have? Got some helpful hints, tips, or tactics we don't know about? Tell us and you could win a free PlayStation game (or any other game you want for any video game system)!