I have this exact game and ive owned it since 1981 when it came out. at the time this was an incredibly advanced game for a handheld. the dots that appear on the side is your fuel gauge. when they appear it means your down to your last bit of fuel. they will slowly dissapear dot by dot until nothing and then you crash. so when they appear its time to get down under 10,000 feet and land. this is back when "high score" meant everything and thats really the only point to the game play. Thanks!
