Rainbow Islands: The Story of Bubble Bobble 2 is possibly Japanese game developer Taito‘s finest hour. On any system.
It was first released in video game arcades in 1987 and was an instant hit, with its brilliantly-drawn, colourful cartoon graphics and rainbow-conjuring gameplay. One or two-player, Rainbow Islands is a treat to play.
These grabs are from the original arcade version, which is probably the best-looking one still. Although there is a fantastic PlayStation/Saturn version with three different versions of the game, including this one. Grabs of that can be found here.