Note: While the cheat is verified, the solution has not yet been fully
  tested.
  When you start the game, run right until you come to the man with the
  spear, press `A' to ask a question, type in "TEN PINTS" and press
  <Return>.  You should now have infinite energy.
  When asked to whisper the password, try whispering either "SUNSTONE",
  "OBERON", "NECROPOLIS", or "ETERNITY".
  Here also is a full solution:
  First you should go left.  Through the trees tossing their balls about
  at you, and across the bridge.  You will now arrive at a tree stump with
  a guard (Don't kill him!).  Here you'll need to be as fast as possible
  to jump up about four times and kill the oversized mosquito that is
  going to carry the guard away.  When he's dead then stand still and
  listen to what the guard says.  Now ask him about "traps" and he will
  say either "Upper" or "Lower".  Now descend the stepped branches to the
  left and jump into the side tunnel on the left.  Walk along until a
  cousin of the mosquito that you killed above will fly past.  Turn around
  fast and go to the right where the mosquito is cutting through the rope.
  KILL him quickly or else you're stuffed.  Once he's dead just stand on
  edge of the ledge and wait for a strong dude to push a stone towards
  you.  When he reaches the very edge where you're standing, hit him once
  and he'll kick the bucket.
  Now go to the left and up the rise where the hovering mosquito is
  waiting for you to kill it.  So oblige it then go back to the right
  where a key has fallen when you swatted the bug.  Take the key the go
  back to the left.  Drop off the edge, walk across the see-saw then jump
  up onto the rope that's hangin' around waiting to be climbed.  Climb it
  and jump off onto the ledge at the top.
  Use that key you found open the way for you.  Continue to the right until
  you come to a wall with two switches.  Now remember what the guard told
  you?  Was it upper or lower?  Hit the switch (with your mace) that the
  guard told you. (ONLY that switch!)  If you killed the guard by mistake,
  the try the upper switch.  If you hit the wrong switch the ground
  disappears and you get you're feet wet.  If you got it right then stand
  still and the cage above you will be lowered.  Stand on it and wait.  It
  will then rise up.
  Step off at the top and go the right, across the pit with the guard and
  the puppy dog.  Continue until the end where you will find a key.  Climb
  a chain from the ceiling to get to a high ledge where you'll find some
  goodies.  Then return back to the pit with the guard and his pet puppy
  dog.  Carefully climb down the chain and when you're near the bottom jump
  to the left otherwise you'll wake the guard which will mean restart the
  game.  Use the key you found above and release Fido.  He'll then scare
  the chicken soup out of the sleeping guard who then goes off to look for
  a better life and a large bottle of scotch.  Hit the bottom lever at the
  right off the pit, then climb back out and return to the cage at the left
  and descend.
  Continue to the left and go back down the rope you climbed.  Go to the
  left until you reach a wall with 3 switches.  These switches operate the
  crane that is above you.  The lower switch moves the crane up or down,
  the middle one moves it left or right and the upper one opens and closes
  the claw.  Now use the crane to pick up the huge boulder where you're
  standing carry it across to the right hand spike and drop it.  It will
  then break up.  Be careful when using the switches or else you'll break
  the boulder and you're knackered.
  Now push the rock piece left over to the see-saw.  Now climb the rope
  and after some practise manage to properly jump off to the other side of
  the see-saw where the rock is launched into the air and lands in the
  suspended cage.  Quickly run to the left and stand on the other cage. The
  rock's weight will then lower it's cage thus raising your cage up to a
  ledge.  Go to the left, chat to the dragon if you like, then whip him
  into a fudge brownie.  Next hit the bag hanging from the branch and the
  original guard's brother will then drop down. Ask him about "ishran" and
  he will then give you a password for you to remember.
  Now return right, down, right, upabit, rightdownabit, right and  you
  should be at the edge of the ledge with the rope at your right.
  Climb down the rope and continue to the left until you confront a big
  lumberjack with a skin complaint.  Hit him until he falls back into the
  acid pool.  Continue until you reach the tavern.  Enter go to the left
  and take the bottle of booze you find.  You can talk to the barman on
  the right but he's rather boring.  Leave the tavern, go right and down
  the stepped branches with the leaping greenies.  Go to the wall with
  the ghostly apparition of somebody's granny behind it.  Speak the
  password that you were told (you did remember it, didn't you ???).
  Then continue on until you reach a big dude who gives you a parchment
  of a prehistoric playboy centrefold to help you while away the time
  on those cold lonely nights.  Now return all the way back to where back
  to where you originally started.  Continue to the right, through the
  forest full of uglies with oversized toothpicks, until you reach an
  area where there are jumping green booger balls.  Make you're way up
  until you confront Simon the Snot-Nose Monster.  Kill him and collect
  the axe that he drops. Look around and you'll find a couple of chests,
  one's to you're left and the other's above to the right.  After you've
  raided the chests then go back down to the ground.
  Go to the rock platform that defies gravity on the left.  Under it you'll
  find a patch of grass that looks slightly different to the rest of the
  ground.  Jump on it a few times until it collapses.  Go down the stairs
  and across to the left.  Run to the left until you wake a guard who
  starts to run off.  Keep running until you reach a wall with a sliding
  floor in front of it.  Stand up against the wall and use the axe you
  found to kill the guard who's winding the floor in before you fall and
  have to restart.
  Once he's dead you can then kill the other guard and break through the
  wall using your mace.  You'll find a chain so go ahead and climb it.
  You'll find a switch so activate it then run as fast as your little
  Reeboks will carry you to the left where you have to activate another
  switch then run back to the right before the timer runs out.  If it
  runs out and you didn't activate the cheat then you'll be a skewered
  corpse.  Go down until you find four cards sitting around playing poker.
  Kill the two on the right and collect the key.  Go left until you are
  caught in a cage.  Don't worry it's harmless.  Wait for the guards to
  take you to a cell.  Once in the cell offer the bottle of booze you got
  from the tavern to the guard sitting outside the cell.  He'll then take
  it and drink himself to sleep so you are then able to bash down the
  door of the cell.
  Jump onto the chain and climb up to kill the guard on the left.  Go back
  down and kill the sleeping guard, take the key and go back up to release
  the prisoner with it.  Now climb up to the top of the chain where you'll
  kill any guard you find and take a rather large ring. Go to the right
  where the prisoners are waiting at a door.  Open it with the other key
  and run along with the prisoners, who should get impaled by the Heavy
  Duty Deluxe Model Stainless Steel Low Calorie Toothpicks.  Then return
  to the entrance up at the ground level.
  You'll need to find your way to the right where there is a bridge. If
  you go right from the entrance and go down the rope and into the water
  there will be a rope that you can climb up to get to the bridge.  On the
  right side of the bridge you'll find a large postman with an equally
  large letter opener.  Get him to follow you back to the bridge.  To do
  this go up close to him then run away quickly.  Once he's on the bridge
  he'll fall through.  Go to the right and avoid the hole in the bridge.
  You'll find a guy who you'll give the parchment and ring to, and he'll
  then give you a rather useful new weapon.
  Go back to the bridge and fall down into the river where you'll get
  sucked in by the whirlpool.  Make your way across and down collecting
  energy (wow) and the Horn.  Go across until you find and angry snail
  sitting on the world's largest magic mushroom.  Ask him about "karamoon"
  and he'll then offer to take you for a ride for 36 gold (which you
  should have collected by now if not, restart etc...) so you accept of
  course.  He'll take you to Karamoon where you go to the right until you
  are at the edge of a great sea.  Blow your horn and your limousine will
  arrive to take you to Zelek's castle where you enter and seek out Zelek
  to take your revenge.
  That's it you've now finished the game and you can live happily ever
  after until Shadow of the Beast III.