Rainbow Islands: The Story of Bubble Bobble 2 (Arcade)

Bub and Bob are back (in human form), with rainbow power!

Error Handler


Rainbow Islands has a basic error handler that prints the error type, the contents of the Program Counter, and registers D0-D7 & A0-A7. To see it, well...crash the game. The game checks for the following (text starts at ): BUS ERROR ADDRESS ERROR ILLEGAL INST. ZERO DIVIDE CHK INST. TRAPV INST. PRIVILEGE TRACE EML 1010 EML 1111 PROGRAM ERROR

Unused Items
While there are a good amount of unused items in the game's code, most of them have been dummied out. With the exceptions of the yellow and green balloons, which work identically to the red balloon, all that's left of these items are their point values.

 I Placeholder Yellow Balloon Green Balloon Scroll Heart Water Potion Green Bubble Yellow Bubble Red Bubble Monsta Bubble maincpu.mw@013E4B=param maincpu.mw@013E4B=0077

Early Graphics
An early version of the letter in the bad ending was placed in the second GFX ROM. Unlike the final letter, which uses a tilemap, every single part of the early letter uses a unique tile. This is obviously unnecessary and makes the whole thing take up a significant amount of space, but there it is.

Anyway, the only two differences are that "changed" was changed/turned to "turned", and a superfluous space before "surface" was deleted.

Objects
More unused Golem frames. The bombs he throws were supposed to slowly regenerate, but since these frames aren't used, they reappear instantly.

BG Graphics


The Best 5 screen, like the Game Over screen, has similarly unused graphics that could have spiced up the otherwise plain text displayed therein. This is just a mockup, as no tilemap has been located in the ROM at this time.

The platforms in Dragon Island have special tiles that would have been curved their shadows, but they were never placed in any of the rounds. The shadows are just rectangles in the final game.

Original Magical Island Arena
The boss arena in Magical Island is larger than it appears in the game. The three topmost platforms aren't accessible at all, and the two platforms below those can't actually be jumped upon.

Power-Up Difficulty Feature
The power-ups in the game (Which follow the pattern of Sneakers, Red Jug, Orange Jug, Red Jug, Yellow Star, Crystal Ball, Red Star, then a special power-up) are dropped from every third enemy in the game. There's unused code in the game to change how often they drop based on the game's current difficulty level: One every two enemies defeated, one every three, one every five, or one every seven enemies. In the finished game, all four of the drop table pointers point to the once-per-three drop table.

Put this code in MAME's rbisland.xml cheat file to reactivate this dropped feature:  maincpu.mw@013E2C=3E3A maincpu.mw@013E34=3E62 maincpu.mw@013E38=3E8A maincpu.mw@013E2C=3E4A maincpu.mw@013E34=3E4A maincpu.mw@013E38=3E4A

Revision Differences
There are two differences with the sets labeled "New" and "Old" in MAME's nomenclature, both of which are related to the secret rooms.
 * The 50,000,000 point bonus for visiting all secret rooms isn't obtainable in the old version, as there's no counter that gets incremented each time the player visits a secret room.
 * It's possible to go above the secret rooms by walking on rainbows. Going past the screen will scroll the screen up to the next bonus area and make the game think that the player is fighting a boss.

Rainbow Islands Extra
Rainbow Islands Extra is a modified board for Rainbow Islands that was only released in Japan. Most of the differences between games is related to difficulty; Rainbow Islands Extra is designed to be significantly more difficult than the original.


 * Each stage's enemy set -- save for Bubble Island -- has been changed in Rainbow Islands Extra:


 * Every round was given a new palette in Rainbow Islands Extra. Some of the bonus items that are part of the stage have been changed as well; The most significant change is that almost all of the Star items past Insect Island have been removed.


 * Three new hints, Hints D-F, have been added, each giving information on the changes from the original game.
 * There's an extra message in the good ending after the player enters their name into the high score table. It's a plot synopsis of "Bubble Bobble 3"! ...or it should be, but this plot doesn't match up with any of the sequel games.
 * This story idea was likely abandoned after Fukio Mitsuji, the designer of Bubble Bobble and Rainbow Islands, left Taito in 1989.

Items

 * The Rainbow Special item, which was available after using 33 credits in the original game, now appears every 800 credits in this version.
 * Not only that, but it doesn't actually do anything in Extra! Its routine has been completely dummied out.
 * The Bronze, Silver, and Gold Scepters appear after collecting 6 of the appropriate crowns in Extra, compared to 6, 8, and 10 crowns respectively in the original game.
 * The requirement for the Red Tiara was changed from 20 enemies killed by the guardian fairy to 50 enemies.
 * The requirement for the Green Tiara was changed from 30 enemies killed by stars to 90 enemies.
 * The requirements for the three Ring items was altered from collecting 3 Red Jugs/Orange Jugs/Sneakers to 12 of those items. This change makes the various Potion items appear much more often than in the original game.

Enemies
Some of the enemies have changed to be less / more difficult, mostly in the early and later islands:
 * The only enemies in Insect Island that fire projectiles are the turrets, and those bullets no longer home in on the player.
 * The Fighter Plane enemies from Darius Island aren't present in Insect Island.
 * The Wizards in Combat Island do not shoot any projectiles.
 * The Caterpillars that were originally in Magical Island are completely absent from Extra.
 * All of the knights in Monster Island are Gold Knights; The regular Knight enemies don't make an appearance here.
 * The Water Gun enemies in Dragon Island can shoot two times, compared to just once in the original game.
 * The number of bombs that the Crate enemies in Darius Island shoot was doubled from two to four.
 * The Cannon enemies in Darius Island can shoot up to three bombs at once, up from a single bomb in the original game.

Bosses
All of the bosses in the game had their difficulty levels rebalanced to match their new location in the game.
 * Electric Fan's ships no longer track the player, and the boss itself only has 10 HP, down from 22 HP in the original game.
 * The Red Devil's trident moves two-thirds as fast in Extra. He has just 13 HP, eleven less than the original game.
 * The Dragon boss has to come to a stop twice, not once, before he uses his flame breath. He has 18 HP, four less HP than normal.
 * Doh moves (!!!) back and forth while firing his deadly squares.
 * The Giant Spider has a new attack: Spider webs shoot out from its butt and fall from the sky.
 * The Giant Vampire shoots out eight bats at once, up from six in the original game.
 * The number of Clowns that the Giant Clown spawns doubled from four to eight. The boss itself moves twice as fast.
 * The Giant Robot has slightly faster rocket fists and fires six energy balls instead of four.
 * The Giant Plane has changed the most, and is significantly harder in Extra:
 * The plane itself moves twice as fast.
 * The Giant Plane shoots out seven bombs, one every five frames, then waits 35 frames. In the original game, it dropped just one bomb every 48 frames.
 * The bombs fall down four times as fast.

Secret Rooms

 * Exiting a secret room without collecting the bonus item nets the player a 1,000,000 point bonus. If the player visits the first nine bonus rooms and doesn't collect a single bonus item, they'll get 50,000,000 points!
 * The point bonus for entering all secret rooms has decreased from 50,000,000 points to 10,000,000 points. If the player collected the Big Bubble item, it's reduced further to 5,000,000 points.
 * The passwords in the secret rooms are not fully visible. The first character is always revealed, but only one of the other seven characters is displayed. That character depends on the last diamond collected in a stage before the boss. So, theoretically, a player would have to visit a bonus room at least seven times to get the full password.
 * Additionally, all of the secret room passwords are different between versions:

Additionally, two of the special items in the original game -- The big wing book and warp doors -- were replaced with newly added treasures.
 * The passwords for Hints A-C aren't given in Extra, but they're identical to the original game.
 * For the first seven islands in Extra, the special items in each secret room are not determined by what island it is. Instead, the treasure depends on the color of the last diamond collected.