To unlock the character I used here (Robolun) you need to first complete all 100 stages with either Bub or Bob (you can swap between the two at any time, doesn't change progress). Robolun isn't required to collect all the letters to play through every stage, unlike Bub or Bob. You cannot access the final ten levels without first collecting all the letters "REVOLUTION". You collect letters by defeating four enemies in one super bubble in a stage, then picking up the key which drops. Be quick to get the key, sometimes it'll fall in an impossible to reach spot. You can however repeat the process as many times as you want up until the boss encounter. This continues for each of the first nine worlds. Once collected you must defeat the boss at the end of the world within one continue/credit to collect the letter. As per the final stage, I don't know what happens once you collect the key there. You can try it yourself with the game save files I've attached below. ROBOLUN UNLOCKED SAVE: LOVELUN UNLOCKED SAVE: The exact name I used for the ROM was ( Bubble Bobble Revolution (PAL).nds ). Yes, this is the PAL version as the NTSC version is broken on level 30 (really).
