Upa is the prince of a magical kingdom and the most recent in a line of brave fighters. One day, though, he broke an urn containing the spirit of Zai, an incredibly evil goatish demon who takes the life force of the kingdom's adults and kidnaps all the babies - except for Upa, who is given a magical rattle by a fairy who was trapped in the urn along with Zai. And so, in order to save his kingdom, Upa crawls into action...
In this game, you control a little baby. The baby crawls through imaginary worlds, made of candy, chocolate, toys, and other things a baby would dream of. It has to traverse those platform levels to defeat or avoid various enemies. The way the baby deals with the enemies is quite unusual: it inflates them. When inflated, the enemies lose control and begin to float, until they finally explode. The baby can use this to its advantage, riding the enemies while they are floating, kicking them to various directions, making them bounce off walls, using them as projectiles to hit other enemies, etc. Such strategies are necessary when dealing with the bosses you encounter. There are various items scattered through the levels, such as milk, which restores your health completely.