HELLO BT21 is a free puzzle game developed by Kakao Games Corp. The game is set in the world of BT21, where the BT21 members are trying to achieve Universtardom. However, their efforts are being thwarted by Popomons, a bunch of interfering dandelions. The game has different stages with a variety of challenging obstacles, including milk, boxes, ice, and slimes, which add to the overall fun and excitement of play. The game is ultra-easy to play, with the ability to fling bubbles at a touch that is super refreshing.

The endearing BT21 characters have special skills of their own that will help you clear each stage and progress through the game. You can also clear stages and collect the sought-after Story Keys, clear the Story Missions with the Story Keys you've collected, and then get cracking on cleaning up the Town. The game has a town feature where you can find and tap a chatty friend from the forest LEAF in Town to get a special BT21 illustration. You can also clear Story Missions and then create your own wonderful Town. Enjoy Hello BT21 together with your family and friends!