Rainbow Islands is a sequel to Bubble Bobble. Protagonists Bubblun and Bobblun now appear in their human forms as Bubby and Bobby. The objective is to climb to the top of each stage in a time limit, while avoiding or destroying various baddies along the way.
The players can summon rainbows which can be used as platforms and weapons. In a TAS, they can be abused greatly to allow dizzying rates of ascent.
This run obtains the bad ending, because it does not collect any of the Big Diamonds used to unlock the secret last level.
Watch this run being played back on a real console.