The circulatory system distributes blood around the body. Arteries carry oxygenated blood from heart to the whole body and veins carry deoxygenated blood from the body to the heart. You are a blood cell that has to go through 2 levels. In level one, you have to go from the heart to the kidney. Level 2 is going from the kidney to the heart. If you complete both the levels you win the game.
