A sequel to Bubble Bobble. You're playing as the human forms of the familiar characters who shoot rainbows at enemies while going up, so it's not just restricted to a single screen like the first. I'd go a little further into the game, but I seem to have forgotten my effective way to beat the first boss without dying even though it's easy to beat.
A limited revision called Rainbow Islands Extra Version was also released, with many of the theming and enemies changed up.