Primary Collection of Cheats
Unlock Alternate Outfits
Hold [B] while on the title screen and enter one of the buttons combinations to change Quote's appearance. If entered correctly, the "Press the A Button to Begin" message will flash. The codes will work for any difficulty setting.
[1], [2], [1], [2], [2] - Red.
[1], [2], [1], [2], [1], [Down] - Yellow.
[1], [2], [1], [2], [1], [1], [1], [Up] - Blue.
[1], [2], [1], [2], [1], [1], [1], [2], [2], [Left] - Christmas.
[1], [2], [1], [2], [1], [1], [1], [2], [2], [+], [+], [-], [-], [Right] - Halloween.
Hints
Unlock Alternate Credits
After making the rocket that leads you to the last cave, do NOT talk to Momorin, but take the rocket and keep your Mimiga Mask. There will be some dialog change after this point and some of the portraits displayed during the credits will be altered as well.
Unlock Sound Test
This should only work on the update or European version. From the Options menu, highlight the music option (the one with the New/Old option) and press [1] to go forward, [2] to go back. While the music is playing you can switch between Old and New to hear the original version or the New version.
Christmas/Holidays Costume
If the Wii's date is December 24 to 26 (set in thw Wii's settings), the appearance of the character in Cave Story would change into a Christmas/Holidays costume (regardless of character selected). The character and his/her costume will be in-game and in the menu.