Bio Miracle Bokutte Upa is a linear side-scrolling platformer. There are 21 stages, divided into 7 Worlds. Each world is 3 stages long. At the end of most every stage is a boss battle that you must complete in order to make a treasure chest appear. You must then shake your rattle on the treasure chest to open it and advance to the next stage. The only exceptions are Worlds 1-2, 2-2, and 6-2, which present you with the treasure chest as soon as you reach the end of the stage.
You begin the game in World 1, and must complete every world in their order, until you complete World 7. There are no warps, and no other abilities to skip stages. There are also no mid-stage checkpoints. If you die anywhere in a stage, including during the boss battle, you must start over from the beginning of the stage. If you lose all of your lives and choose to continue, you will start over from the beginning of the first stage in the last world, even if you died in the second or third stages.