The Heart Balloon is an upgrade gives you a heart-shaped balloon that floats above you. As long as you hold the balloon, your fall rate is reduced. If an enemy touches the balloon, it will explode, killing anything in the blast radius. If the balloon pops, it will reappear on the next floor.
Heart balloons have a chance to appear as an upgrade after completing a level.
After equipping it, a new balloon is given at the start of each level.