"SKULLDUGGERY" step-by-step solution by pjg
For game release 3.1
Takes about 380 moves.
Comments and points/total points are given in ()

The brief solution overview
1) Darkness: Start a fire in the kitchen with the logs and the sulfur or hay.
  Use the flint and iron to start it.
2) Read the parchment from the cellar to find out the ingredients for the
  potion. The nine ingredients needed and how to get them are as shown
  below.
3) Ashes: Use the crowbar from outside to pry open the marble coffin lid.
  Get Charles' body and put it on the Ouija board. When in Hades, put
  Charles' body on the altar. Get the ashes and put them on the ouija board.
4) Hair: Move the slab in the mausoleum. Use the knife to cut the hair of
  Lord John.
5) Blood: Drink the wine or brandy to have a dream about secret passages.
  Turn the moulding in the billiard room to reveal the secret passage.
  Go up to the attic and get the stake. Get the shovel and a bottle.
  Go to the grave yard and dig up Henri's grave. Kill him with the stake.
  Put the blood in the bottle.
6) Spider: Turn the moulding in the conservatory. Go up and get the spider.
7) Finger bone: After getting the spider, go down to the smuggler's lair.
  Enter the dungeon cell. Cut the finger with the knife or cleaver.
  Use the finger bone to unlock the cell door.
8) Old bones: After getting the finger bone, head east to the cliff
  overlooking Hades. Use the torch and the candle to provide light in
  adjacent rooms. In a "leapfrog" manner, transfer the bones and the light
  sources N, W, S, and U. Transfer the bones to the kettle. This is best
  when done during the day.
9) Black skull: During the day, move the black skull from the master bedroom
  down into the kitchen kettle.
10) Beast soul/heart: Take the knife or cleaver and go wander in the east
   forest. Eventually you will fall into an animal trap pit. Cut the heart
   from the wolfdog.
11) River water: When in Hades, open the pocket and get the gold. Sit in
   the boat and give the gold to the boatman. While crossing the river,
   get the jar, open it, and fill it with water. Put the jar on the Ouija
   board.
12) Put all nine of the ingredients in the kettle. Put the potion in the jar.
   Take the shovel, crowbar, and jar to the lonely grave. Dig up the grimy
   skeleton and take it to the mausoleum using the secret forest trap door.
   Pry open the granite coffin lid. Put the skeleton inside and pour the
   potion on it. This will unlock the ship cargo hold trap door and give
   you a gold key.
13) Go to the ship on the beach. (Turning the ship's wheel opens the powder
   locker) Open the cargo door, go down and unlock the chest. Open the
   chest and then enter it for the surprise ending.
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Read the SKULL.DOC file for some background information first.

Multiple commands are given on one line, even the the game only accepts
one command per line.

Gates and doors will randomly close, open them as needed.
If the front gate blows shut **before** you have entered the estate
then you must restart the game. You can't win if you are stuck outside.

You can be killed randomly, restore a saved game to avoid this.

The Grim Reaper will sometimes appear too early. Restore a saved game
if you have not put the ashes and the water jar on the ouija board.

Do not have more than 1 "quantity of water" at any moment in time.
(database gets confused)

Do not put objects into the burning fireplace.
(you end up carrying the invisible "burned" object)

Drinking the brandy and the wine will show you 2 of 4 dreams.
Restore a saved game and redrink until you see all 4 of them.
------------------------------------------------------------------------------

(you start with 1 point already) (1/26)
Get bag
SW. Read plaque
(if the gate is closed then restart the game)
S
(the gate will always close after we pass through it.
I never did find a key for this gate.)
Drop bag. Open bag
Read newspaper. X me.
E. Read note.
W, S, S, S
Open door
S. X tabard.
E. Get candle
S, E. Get book.
W, S, W, W, W
Get decanteur
Open decanteur
E, S, S
Open door
save 0

(we will use the kitchen as our base of operations)
W
Open cupboard. Get all
(we will use the cleaver instead of the boat knife)
E, S. Get logs. N
Put logs in fireplace
Put sulfur in fireplace
(we could have used the stable hay instead of the sulfur)
Get flint. Strike flint on iron
Drop all
save 0

N, U, E, S
Get skull (2/26)
(do this in daylight)
N, W, D, S
Put skull in kettle
Light candle with fire
save 1

N, U, E, S
Get bible
N, N, E
Get torch
Light torch with candle
E, S, S, N
Get diary
S, NW, W, W, W
D, D, N
Get parchment
S, S
Get bottle
Open bottle
N, U, S
save 1

Read diary (Charles betrayed William)
Read book  (William's ghost needs a Druid sedation potion)
Read bible (Lord John was a Druid wizard)
Read parchment (here are the potion ingredients)
Drop all
save 2

restore 2
(do a few I's or L's to waste a turn or two
to change the random dream)
Drink wine
Drink brandy
(keep on restoring and drinking until you see all 4 dreams)

Get candle
Get torch
Get cleaver
save 2

N, N, E
E, N, E
Turn moulding
S, U
Pull lever
N (3/26)
Get spider (4/26)
(If the panel closes then
Turn moulding
to open it again)
S, D, D, S
save 3

(X skeleton. Again)
(until the skeleton speaks to you)
S (5/26)
Find finger. Cut finger with cleaver (6/26)
Get finger. X finger
Unlock door with finger
Open door
N, N, E
E, S, U
Drop all
Get candle
Get torch
save 3

Enter
N. Drop torch
E. Drop candle
S. Get bones (7/26)
(guess who the hooded figure is)
N, W
Drop bones
E. Get candle
W, S
Drop candle
N. Get bones
S, U
(it must be day for you to see)
save 3

D, W, N
Open door
N, N, W, W, S
Put bones in kettle
N, E, E, S
S, S, E, U
Enter. Get candle
N. Get torch
S, U
Get all
D, W
Drop torch
(we don't need the torch anymore)
Get bottle
Open bottle
save 3

N, N, N, E (8/26)
Turn moulding
N, U, U    (9/26)
Open chest. Get stake
D, D, S
(pull the lever if the panel closes)
W, W, W, S
Put finger in kettle
Put spider in kettle
Open door
save 4

S, W
Open side door
W
(we could have used the hay instead
of the sulfur to start the fire)
Open stable door
N, N, N, N
Get shovel
S, E, W, W, S
X grassy grave
Dig grassy grave with shovel
Again
X Henri
Kill Henri with stake
Drop stake
Put blood in bottle (10/26)
save 5

E. Open door
W. Move slab (11/26)
W. X John    (12/26)
Find hair. Cut hair with cleaver (13/26)
Get hair
E. Open door
E, E, E, S
S, E, E, N
Put blood in kettle
Put hair in kettle
Drop red bottle
save 5

N, N, E, E
Open door
E. Read monument. E
save 6

(movement in the forest is random.
the directions given here may not
for you)
SE, W (we want to go to the southern rolling meadow)
Get hemlock (we don't really need this, but it is useful)
N, E, N (we want to reach the animal trap)
X dog
Find soul. Find heart
Cut heart with cleaver (14/26)
Get heart. Drop cleaver

D (15/26)
Again (keep trying until you reach the underground tunnel)
NE. Open trap door. U
save 6

N, W, W, W, S
Get crowbar
N, NE, NW, N
X floor
Pry floorboard with crowbar
Get key (16/26)
S, E
Read cross
Dig grave with shovel
Again
Drop shovel
Get skeleton (17/26)
W, SE, E, SE, SW
D, SW, SW
Unlock trap door with key. Drop key
Open trap door. U
save 6

SW, SW, W (we want to return to the garden)
W, W, W, S, S
Put heart in kettle
Open door
save 6

S, W, W, N
N, W, W, W
X granite coffin
Read granite coffin
Pry granite lid with crowbar
Put skeleton in granite coffin
(this unlocks the trap door on the ship)
X marble coffin
Read marble coffin
Pry marble lid with crowbar
Drop crowbar
Get charles (18/26)
E, E, E, S
S, E, E, N
save 7

N, E, E, E
Look on the board
Touch planchette
Again
(do this again and again until
"Translation platform" is spelled out)
Put charles on board
W, S, S, S
Drop all
save 7

Eat hemlock (19/26)
(we had to wait for the right moment)
X shroud. Open pocket
Get gold (20/26)
Sit in boat
Give gold to boatman
Wait
Get jar
(actually, you can use any container)
Open jar
Put water in jar (21/26)
save 8

N
Look on the board
Get charles
(if the grim reaper appears and sends you back,
then restore, waste a turn or two and try again)
E (22/26)
Put charles on altar (23/26)
Put ashes in jar
W
Put jar on board
(now we have to wait around for
the grim reaper to send us back)
save 8

Read plaque
X man
(guess who the figure is)
Wait
Again
(until we are sent back)

Get candle
N, N, N, E
Look on the board
Get jar
W, W, W, S
I
Put ashes in kettle
Put water in kettle
Look in the kettle
Put potion in jar
save 9

S, W, W, N
N, W, W, W
Pour potion on skeleton (24/26)
Drop jar
E, E, E, E
S, E, S, S
W, U, S
(Turn wheel)
(Enter. Open cupboard. Exit)
Open trap door
D (25/26)
Unlock chest with gold key
Drop key. Open chest
save 9

Enter chest (26/26)