Cheat:

  The  level codes: MANDTIDS = Frozen Wastes,
  CICADAS  = the Dead City, PSYLLIDS = the Wood World, PIERIDS = the Kaverns,
  SATYRID  =  Death  Valley, LYCAENID = Creeping Swamp, PYRALID = Tech World,
  NOCTUID  =  Transluscent  Plain  and NO PASSWORD! of course for the Stygian
  Creek. Press the 'UNDO' key until the words "Cheat on" appear. Now, as long
  as  you  don't  lose  a  life, you will have infinite energy. Also, you can
  press  'SPACE' on the title page to enter a secret code: JUPITOR = Infinite
  time, PLUTO = Infinite ammo, FREEPLAY = Infinite credits and LISTEN = Sound
  test.