GIGANOID:

        On the player select screen, press the 'CAPS LOCK' key, so the key
        light is on.  Now press and hold the 'CAPS LOCK' and press fire.  A
        message should appear letting you know the cheat is active.  If you
        held down the fire button a little to long the game may have
        started and bypassed the message, but you should notice you have a
        lot of lives.