Spaceguard

Your spaceship is patrolling a sector of space where aliens are laying mines. Your task is to destroy the aliens whilst avoiding collision with them and the mines.

You have an unlimited fuel supply and can fire at any hostile object with your lasers. You will get 150 points for each alien you hit and 50 points for each mine. Each time you clear a screenful of aliens you are awarded an extra 1,000 points. At the start you have three ships but every time you score 10,000 points you gain another ship.