At the main menu, select the "New Game" option, then enter "GREYTHERAT" as saved game name. All levels, including the bonus levels, will be unlocked. Enter "M1A2U3L4!?" as a saved game name to unlock all levels until Darth Maul. -From: firstname.lastname@example.org
Defeat Darth Maul in level 25 to unlock the Battle Royal mission, where you have to fight eight other Jedi Masters in the Saber Arena.
Defeat a character in the Jedi Arena during the game to unlock him or her in versus mode.