Your ship ran out of power and you are kept from the gravity of an asteroid in some planet-system. The only way to escape is to get the energy balls from the mountain at your right and collect them into your spaceship.
You have the opportunity to put a ball in your spaceship when the door is opened. Otherwise you have to wait until it is opened again. In time you will realize that "waiting" does not mean "staying and doing nothing". The aliens have spread for you a lot of traps in this cold corner in the outer space.
There are two levels of difficulty, G1 and G2 (game1 & game2), set through the button [MELODY/LEVEL] from the main menu. Playing in the second level there is the opportunity to save your scores and upload the highest of them to the public high-scores table found in the website of the game http://www.spaceballthegame.com