Your goal is to destroy colorful blocks on the tower, making it shorter until it reaches a target height. Click on a block to shoot a colorful cannon ball at it. Make sure your cannonball and the block are the same color, otherwise it will have no effect! 

If you need a better angle, click and drag on the screen to move the camera around the tower. When you earn enough points, your cannonball will turn into a giant asteroid. Use it to take out many blocks at once! Earn coins and spend them on more powerful upgrades.