The little kitten Kitty, her kitten friend Mimi and their bear friend Tippy love playing with balloons. One day, Tippy has inflated a whole bunch of balloons when suddenly a strong wind blows. Tippy is blown away! The only way for Kitty and Mimi to find their friend again is to pick some balloons and fly to her rescue.

Hello Kitty World is quite similar to Balloon Kid – a forced side-scrolling platform adventure where you control a character floating around with a balloon in the hand. Kitty (or Mimi) starts out on each level with two balloons, and by pushing the A button, she moves upward before sinking again if the button is not pushed again. When Kitty comes in contact with an enemy, she will just rebound, but she will fall to the ground if both balloons are hit. By pushing the B button, Kitty can also choose to let go in order to walk around like a normal platform character. This is necessary in order to reach power-ups and hidden areas. Since the scrolling is forced, it is easy to go get stuck and pushed off the screen.

Throughout the levels, Tippy has dropped balloons that can be picked up for points. If twenty balloons are picked up in succession, they turn into double balloons worth more points. Enemies come both in the airbourne and ground-based varieties, along with some fish that can surprisingly jump out of the water. Some enemies can only fly by holding balloons, and just like in Balloon Fight, these can be disposed of by touching their balloons.

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