Start New Game.

ACHIEVEMENT - HALLOWEEN
When it asks you what day it is, enter 1031
Enter Castle

4x Candy on first floor
Talk to the butler up the stairs to get a Flashlight. (Just walk around with the flashlight on)

Downstairs and to the right corridor
5x barrels
Enter the brown door.
x2 candy
Walk to the head of the bear rug and take the Key to the Kitchen from its mouth.
Walk to the mounted head on the wall and try to jump to get what's on it.
Walk to the bottom right and pick up the stool, bringing it back to the mounted head to get the Locket.
Talk to the ghost on the rug and answer "She loves you." Pick up the White Rose off the ground.

Leave the right corridor area, and go to the left corridor (two screens to the left)
1x Candy and 4x barrels
On the first brown door (middle room) your answer may be any type of food. You can answer "Pumpkin" if you would like to see a bad ending to the game, but you won't get anything for it other than privilege of seeing a different ending. Credit for finding this goes to 'Just a Stranger' as seen in the comments! Thanks! Achievement hunters: enter something else so you can get the good or true ending.
Use the Key to the Kitchen to open the second brown door (top)
Enter the kitchen and grab the Blue Potion from the closest shelf. Save this to use after the True Ending for an achievement.
2x barrels
Wait until a ghost enters (or click on the red wine shelf) and asks you to bring wine. Grab the Red Wine from the shelf and bring it to the Dining room (first brown door). Hand it to the ghost.
You are now in the dining room.
x7 candy
Open the cupboard with an answer of 5 and you will get the Key to the Cloakroom.
Exit the dining room and then go back into the dining room, but say "dinner is ready."
x3 candy
Talk to the ghost and say "sure" to get the Sticky Table Clothes. Leave the dining room and go back to the kitchen (second brown door). Walk to the sink to get Soap. Leave and go the bathroom (green door) and wash the clothes in the sink there to get a Magazine Page. Leave and go back to the dining room, entering with an answer of "It's ready," and talk to the ghost.

Leave and go right two screens to get to the right corrider again.
Use the Key to the Cloakroom on the Green door (Cloakroom). Enter. Interact with the empty stool in the middle of the room.

ACHIEVEMENT - FASHION LV.999
Match an outfit for the invisible ghost of all the same color. Like a slot machine, jut click to select all three outfits of the same color such as red, purple, etc. You can continue to match outfits like this to get candy, but don't bother as the amount of candy you have is pointless.

You will receive an Invitation. Look at the invitation in your inventory to see what room number you need to enter to get upstairs in the main hallway.

ACHIEVEMENT - RIDDLE ROOM
Exit the Cloakroom and go to the upper right corner, near the three barrels, and interact with the top wall to find a secret door. Keep bugging the voice until it asks you if you like puzzles, select "yes." The answer is "RIDDLE"
x10 candy in secret room.

Leave to the right and go back to the center room, up the stairs, to the left. Tell the person your room number. You are now on the second floor.
x5 barrels

You are on the second floor.
Enter the room to the left (Library).
x3 candy
Release the book on the left and you will get a Blue Book.
Leave and go interact with the blue door. When asked if you have it, say "yes" and give them the Blue Book to enter.
x3 candy
Interact with the blue doll, and then put the book on the left bookshelf.
Leave and enter the Pink (looks purple) door. Some shoes will run by as you enter.
x3 candy
Interact with the pink doll and then you're off to find shoes.
Leave the room. Door to the right is locked. Head back down to the first floor. Go down the steps and head back to the left corridor. Follow the shoes to the end of the corridor and grab them to get Red Shoes and Doll Feet. Head back to the right wall and interact to find the secret door to the dungeon.
x3 barrels
Look under the stretching table (near save point) to find a Dirty Key. Use the key to open the passage to the right.
Enter the dark passageway.
x6 barrels and x3 candy
Go to the Red Pool and use the item White Rose to get a Red Rose. Also use the Red Shoes here to get the Doll Body.
Go to the upper right corner and you will find a Doll Head on the top wall near the skeleton bodies (above the coffins).
Talk to the person and a door appears behind them. Go in to the torture chamber.
x2 candy
Read the sign, talk to the three costumed prisoners, walk to the guilloteen and select "Skeleton" to get the Silk Heart. Interact with the mirror.
(Cinematic)
Talk to the three mirros and exit through the top mirror to the third floor.
Enter the Green Room.
x3 candy.
Put the doll back together and give it the Silk Heart from your inventory.
Leave and enter the Red Room.
x3 candy.
Navigate to the Red Doll and give it the Red Rose.
Leave, go downstairs, and go back into the Pink room. Give the Pink Doll the Doll Feet.
Leave. The door to the right (Game Room) will unlock. Go in and talk to the rabbit.

ACHIEVEMENT - TIME
When the rabbit asks what was killed in the room, answer him with "Time"

x2 candy
Look in the fire. Grab the Old Cue from the billards table.
Use the Old Cue on the fire to get the Clock Key.
Use the Clock Key on the cabinet to the far right and go in.
x1 candy
Go left and grab the clock off the table that is only right "twice a year"
Head back upstairs and leave the clock room. Give the clock to the rabbit.

Pink Doll (looks purple) - Harp
Green Doll - Dart
Blue Doll - Piano
Red Doll - Billiards

Run upsairs. New set of stairs to go up.
Down hallway and through door.
Click coffin - choose to stay for True ending, but must beat timer.
Choose to leave for Normal ending.
Push furniture on far left, revealing secret passage. go down.
Character will fall asleep after a few seconds in room.
(Cinematic)

ACHIEVEMENT - POTION
If True Ending, after the girls are reunited in the pumpkin room use the Blue Potion from your inventory.

ACHIEVEMENT - TRUTH
This achievement is given after the credits when you beat the game.

ACHIEVEMENT - CANDY
Total of 50 candy bags and 25 barrels to break.

ACHIEVEMENT - STEAM PUMPKIN
After completing the game with the good ending, click Extra in the main menu options. Go to the upper left corner and open the chest to unlock the different outfit. Go back to the main menu and start a new game. Select to equip the new outfit upon game start.