Quickly press [Up], [Down], [Alt], [Ctrl] at the endless mode main menu with "Fever", "Mission", and "Original" options. A sound will confirm correct code entry.
All single player mode characters
Quickly press [Down], [Up], [Ctrl], [Alt], [Enter] at the single player mode difficulty selection screen. A sound will confirm correct code entry.
Characters from Adventure Mode
In Adventure Mode, clear all 10 stages in the following chapters to unlock certain characters to be playable in other modes.
Character
How to unlock
Draco-Centauros and Witch
Clear Chapter 5.
Ecolo and X
Clear Chapter 7.
Lemres and Satan
Clear Chapter 6.
Schezo and Feli
Clear Chapter 4.
Master code
Enter the options menu and select the "Gallery" option. Highlight the "View Cut Scenes" option, then hold [Ctrl] and press [Up], [Down], [Left], [Right] to unlock all intermission sequences and bonus characters. A sound will confirm correct code entry.