"Hey, over here!!".
The enemies around are trying to destroy these balls and you. Some of 'm drop mines that roll after the balls, when that happens your hear a whistle, the mine shows up in your mini-map at the bottom of the screen together with an arrow to show the fastest way to get there. Be quick! Other enemies just chase you and if you shoot 'm with your laser they explode into multiple smaller ones!
And then there is the extreme fast UFO that emerges out of thin air after a couple of minutes, so don't take too long! This is a tough one to kill.
This 2D scrolling game is great fun and you've got to be real fast. Keep flying in one direction always brings you back where you started off, so watch your mini-map closely, you'll have to decide very quickly what the shortest way is to get to the endangered scientist.