Access Bonus levels:
At the classic mode title screen, press L, R, L, R, L, R, Right, Select. Level 20 will now have a door in it. Touch it go start the bonus rounds.Powerop mode:
At the classic mode title screen, press Select, R, L ,Left , Right, R, Select, Right.Super Bubble Bobble:
To unlock the a harder difficulty in classic mode, you first must beat the last boss using 2 players. Then at the classic mode title screen, press Left, R, Left, Select, Left, L, Left, Select to unlock the harder version.Unlock Robolun:
Beat all 100 levels in the new version of the game, and he should appear at the character select screen. He's faster, but can't jump as high.Unlock Lovelun:
Using Robolun, beat all 100 levels in the new version of the game again. This will unlock Lovelun, who shoots bubbles farther and faster than normal.
Thanks to Revolution Reader Nerdlun!

Embark on an inspiring mission of human connection beyond the UCA. Sam — with companions by his side — sets out on a new journey to save humanity from extinction. Join them as they traverse a world beset by otherworldly enemies, obstacles and a haunting question: should we have connected?