Quoted from Heater:
Sorry for such a dumb question. What do the mini skulls stand for in each of the move chapter slots across the backscreen. Is that part of the skull hold? Thanks
the mini skulls appear after you qualify that color by hitting the shot associated with it (left ramp for red, spinner for purple, etc).
when you hit the star map shot to start a chapter, any of the 'mini skulls' you have qualified will be the random choices the magnet ball chooses between.
if you complete a chapter you get a check mark in that skull spot. if you fail to complete the chapter you get an X in that spot.
i believe you can build the value of the chapter by hitting an individual skull shot multiple times to increase the multiplier value before you start the chapter.