Planetoids

On your way home back to your planet in your spacecraft, you have encountered an asteroid field with the asteroids together in clusters. Viewed from above, you scroll down the screen as the asteroids move upwards but you are able to move left or right and shoot them with your destructer. Your main problem though is your craft only has 500 energy units remaining and you need at least 100 to land on your planet. Every movement you make, firing the destructer or using shields when you hit an asteroid decreases your energy and when it reaches below 100 then it is game over.