Rainbow Islands

Rainbow Islands is a sequel to Bubble Bobble starring Bubby and Bobby, the human forms of the first game's protagonists, Bub and Bob. Bubby and Bobby must rescue the denizens of Rainbow Islands, who have been imprisoned and turned into Bubble Dragons by an evil villain. As opposed to Bubble Bobble, where enemies were trapped in bubbles, to defeat enemies in Rainbow Islands the player must shoot rainbows at them.

Gameplay
The player controls Bubby or Bobby, who must make it to the top of the stage. Bubby and Bobby have the ability to shoot rainbows, which can defeat enemies, collect items, and act as platforms. Bubby and Bobby can collect power ups that allow them to shoot rainbows faster, increase their speed, or to increase the number of rainbows they shoot. If the player takes too long to clear the stage, the sea level begins to rise. If Bubby or Bobby touch the water, they will lose a life. After reaching the top of the stage, Bubby and Bobby move on to the next one.

There are 10 islands in total, each with their own different theme. Each island features four levels with a boss at the end of the fourth one. The last three islands are not available at the start, they must be unlocked by collecting the seven big diamonds which are only obtained by collecting the seven small diamonds which are dropped by enemies. Enemies will drop diamonds if a rainbow is dropped upon them, or if they are defeated by using certain items.

After collecting the seven big diamonds, Bubby and Bobby may continue on to the secret islands, all of which are themed after other Taito games. To achieve the best ending possible, Bubby and Bobby must collect seven more diamonds on each island, which will make the boss drop one of three mirrors. After clearing the remaining islands, Bubby and Bobby will face off against the Boss of Dark Shadow, who is a giant armored Bubble Dragon. After being hit enough times, the Boss of Dark Shadow reveals his true form: a giant Baron von Blubba. After destroying the Baron, Bubby and Bobby use the gems and the mirrors to transform the villagers of the Rainbow Islands back to their human forms.

Plot
Bubby and Bobby set off to rescue the inhabitants of the Rainbow Islands, who have been turned into Bubble Dragons by the evil Boss of Dark Shadow. They must collect the big gems and mirrors on the ten Rainbow Islands and defeat the Boss of Dark Shadow to return the islanders to normal.