Bonus items:

Enter one of the following initials at the high score screen, then start a new game to unlock the following items and effects.
Beer mug (pizza instead of bubbles)
Enter KTT as initials.
Flamingo (pink worms instead of bubbles)
Enter STR as initials.
Fork (enemies turn into fruit)
Enter SEX as initials.
Knife (enemies turn into various items)
Enter ... as initials.
Octopus (wooden stakes instead of bubbles)
Enter TAK as initials.
Soda can (enemies turn into various items)
Enter I.F, KIM, MTJ, NSO, or YSH as initials.

CPU Controlled Bobblen

Defeat the last Boss in level 100. Start a new game, press Start and select the 'Bobblen' option. This can be repeated after Bobblen runs out of lives.

Cheats

Original Mode for Old that allows you to access secret rooms even if you die. Enter at Old modes title screen: L, R, L, R, L, R, RIGHT, SELECT Power-up Mode for Old. Enter at the Old Mode title screen enter: SELECT, R, L, LEFT, RIGHT, R, SELECT, RIGHT Super Game mode – Old. Beat boss in Super mode with 2 players. Enter code at Old title screen: LEFT, R, LEFT, SELECT, LEFT, L, LEFT, SELECT Super Mode – New. Select a save file, and go to the New title screen and enter: RIGHT, R, LEFT, L, SELECT, R, SELECT, L



Unlock Super Mode (Old Mode/Version)
Go to the title screen of New Version and input RIGHT, R, LEFT, L, SELECT, R, SELECT, L to play Super Mode on New Mode. Start a game on Super mode in the New version of Bubble Bobble and opt to quit (give up). Once you are on the New Versions title screen, press B to back-up. Choose the Old Version and Super Mode should be playable.