On the title screen, type "HELPMARK" for a level select screen.
        Press [1-9] or [A-B] to select the level you want.

        On level one go through the first door as usual.  Then go to the
        far right bottom and jump up to go through a secret wall to get
        a special weapon, then exit.  When you re-appear, jump on the
        spring at the bottom left and just as you start flying upwards push
        up so that you hit an invisible block with a door on it.  Now go to
        the right across the floating platforms, but instead of going
        through the door as normal, stand on the edge above the door and
        fire the weapon.  Another invisible block should appear jump on
        this block.  Then jump up left and walk across the top of the
        screen to the first secret block and go through the door and you
        will enter a secret warp room.