Rainbow Islands is an action-adventure game that follows the story of Bub and Bob, two small boys who must rid the Rainbow Islands of bad guys. In 2-player mode, they work together to defeat enemies and collect gems while navigating four levels each island with a final boss at the end.
The gameplay involves using the power of rainbows to trap enemies underneath, then jumping on them to break them, allowing for the collection of seven different colored gems. There are also power-ups available for extra speed and additional rainbows, which aid in the boys' quest to save the Rainbow Islands.