Use the arrows keys to move. Avoid the rain by timing your movement. If you touch the rain you will lose a life. If you run out of lives you die. Every eight seconds you get a single point. You can touch the clouds but you might touch the rainwater so it's not really worth it. When you touch a heart you get one point and one life. If the 'animation' of rain cloud isn't working just click the flag again.
After a while the background stops working properly.