(LEVEL CODES)

                   LEVEL 2_________________"170961"
                   LEVEL 3_________________"010655"
                   CORE  4_________________"610169"

Tips:  Once in the core, you can't quit.  So choose droids with good
lasers, Jack and Spud for example.  The Quadralien mother is made up
of 4 separate pieces grouped together and surrounded by Earthling
boxes.  The mother can only be destroyed by blowing up each box from a
different direction.  From the starting point there are three exits:
north, east, and west.  Go east and destroy the first box, return to
the starting point, and go north to destroy the second box.  You will
now have both droids to blow the remaining boxes.  Go west through the
one-way force field, and get the other.  Don't forget to keep
recharging.