When you open a treasure chest hold down the 'HELP' key, then when
        you open a second chest hold down the 'INSERT' key.  A golden cross
        should appear, collect this and your health points should rise by
        50,000.  You will also have super shots for the remainder of the
        level.

        To avoid tricky levels, pause the game and wait for three minutes.
        Press fire and all the walls turn to exits.  This happens anyway,
        but if you pause the game, you don't lose energy, and won't get
        attacked while waiting three minutes.