CheatCodes.com has all the official MLB '99 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 MLB '99 are shown below.
At the player creation screen or during spring training, enter "Scott Murray" or any other development team name (located in the back of the instruction manual) as a player name.
Create a player that is sixty inches tall, small build, and has zero attributes.
Enter the start menu and allow the MLB '99 demo to run. Watch it until one half of the inning is over, then a special FMV sequence, along with the credits will appear.
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