Wai Wai World is a strange game created by Konami. They have mixed together components from many of their previous games, such as Castlevania, Goonies and Twin Bees - components such as characters, enemies, levels and theme musics.
Wai wai is Japanese and means "ruckus".
Note: The vertically scrolling level has some anomaly in scrolling if watched with old versions of FCEU. Versions of FCEU from 0.98.13 onward should display this stage correctly.