Mappy Kids follows the story of Happy , Mappy's son, who wants to settle down with a wife. However, she won't agree to marriage until he can prove that he can provide for a family. Happy must collect a small fortune to achieve this goal, but is hindered by the boss cat Nyamco and his legion of Mukies .
The game is a basic sidescrolling platformer where Happy can defeat enemies by kicking them, jump and spin his tail to glide in the air. Throughout levels, treasure boxes and coins are scattered which earn money for Happy, useful for buying domestic items. Conversely, every time Happy is hit by an enemy, he loses some money, with a money bag appearing to recover lost funds.
After each stage, Happy is presented with a slot machine ran by Nyamco . The prize depends on the wheel spin, ranging from extra lives to domestic items. To win these prizes, Happy must participate in minigames against one of the Mukies. These minigames include waving flags, pushing each other off a platform and spotting differences in a picture.
After completing a stage, Happy visits a shop where he can buy items for his house. Purchasing these items will prove to the bride-to-be that Happy is worthy of marriage.
The two-player game pits both players against each other to collect the most assets, with one player controlling Happy and the other playing as his brother Rappy .