In this bonus level dozens of ammo-storing stars swirl onto the screen in front of you. Press ESC to quit game back to title screen. The Spitters will not appear for a long time. Use these levels to practice moving around the grid and shooting accurately. On the higher levels they appear more quick and in greater numbers.
Time is of the essence.
Further into the game your ammo levels will become crucial, so on the early levels it is worth amassing as much ammo as possible. A level will not end until your last shot has dissapeared. This feature can be exploited to shoot any stars remaining on the star tree at the end of a level.