To get this achievement, you must first locate each of the seven VHS tapes. (See the "Dwayne's memento master" achievement for locations.) Put it into the VHS player to the left of the TV in the living room(not the basement), and the TV will play a short video clip on repeat.
The video clip gives hints to where in the house you must go and what you must do to start the chosen storyline. Each VHS has its own storyline with new areas to play through. At the end of each you will find a small piece of blank metal - a piece of the Mirror Mask.
Obtain each of these seven pieces, and the achievement will pop!
Note: The Mirror Mask will slowly be assembled in the progress room, so you can track your progress.
How to get the individual Mirror Mask pieces after playing the required VHS tape:
Pride
Go to the entrance hallway, pick up the Omega Key from the glass. Go to the garage attic(the door next to the progress room), and move the tool drawers on the right side. Crawl in through the small space, and use the key to open the Omega Box. Pick up the handle. Go to the basement, in the area with the mannequin. Between two shelves you'll find a hatch. Use the handle on the hatch, open it, and jump down. Interact with the top of the counter to get up on it, then grab a chair and break the glass. Pick up the emergency axe. Interact with a chair to crawl back up into the room you came from. Use the axe on the opposite wall where the tiles are broken. Equip a lighter and go in. Get through the passage, climb up, and you're back in the garage. Look down into the hatch again and pick up your Mirror Mask piece.
Negligence
Go to the basement TV. On the wall there is now a record placed inside one of the picture frames. Pick it up, and put it in the gramophone. Play the gramophone, and then enter the newly opened passage. Grab the shopping cart and start moving forwards. Fill your shopping cart with beer until it's full, then just continue into the darkness. Drink beer until you get your Mirror Mask piece.
Prison
Go to the basement, in the area with the mannequin. Go into the corridor where the walls are being worked on. The lights will go out, and when they come back on you're in a slightly different corridor. There are two rooms on each side. Go straight ahead and pick up the sledgehammer. Break the brick walls in all four rooms. (Make sure to get the "Special gift" achievement now!) The sledgehammer is now broken. Go to where you first picked it up and interact with the wall to pick up your Mirror Mask piece.
Addiction
Go to the master bedroom. You'll see a hole where the bed was. Go down. Interact with the bed sheet where it seems like someone is sleeping. Go to the TV and sit down. Take a drink every time you're prompted to. At the end you'll get your Mirror Mask piece.
Greed
Go to the boiler room in the basement. Interact with the small stepladder. Interact with the vent cover. Go to the electrical room and grab the stepladder there. Bring it into the boiler room, and use it to get into the vent. Once in the office, interact with the document. Go through the door. Navigate the maze of people to its center, then interact with the bird to get the Mirror Mask piece.
Indifference
Pick up picture frame from ...
1. ... behind the chair in the progress room.
2. ... the wall in the kitchen hall(where you lift up the fallen chair by the door).
3. ... the floor in the closet of the master bedroom.
4. ... below the mirror in the back of the storage room.
5. ... among the garbage bags in the electrical room.
6. ... the ceiling corner above the freezer in the basement.
Place them all on the wall at the bottom of the stairs down from the kitchen, then interact with the pictures to go through a door. Move forward until you get to a room with a chained door and a small table. Swallow each of the five pills. Try to go through the door. Open each of the other four doors. Go through the unchained door. Move through the room with all the words. Turn around a couple of times until a cutscene starts. After that, walk forward to the boat, and get in. Row to the lighthouse, and get off. Enter the lighthouse, sit down by the TV. When done, move to the top of the lighthouse. Interact with the picture. A long cutscene will play. In the darkness, find the door with the chair next to it. Look at the chair and pick up the Mirror Mask piece.
Affliction
Go to the mirror room(unlocked at the start of Dolores' chapter). Use your crowbar to pry open the floorboards. Drop down, go through the tunnel, and enter the door to the factory. Move to the far end, then up to the right. Click the button to open a new passage. Go back and through the new passage. Go through the door. Go up the stairs to the left and enter the cafeteria. Grab the key, then try to go back. Go back into the cafeteria, then onto the table and into the vent. Climb through and exit the vent. Go into the locker rooms and open the bloody locker with the key. Pick up the keycard, and move back out. Use the keycard on the card reader to unlock the door, then move through this door and the next. You're now in an area with water, a tree, and a well. Go to the well and watch the cutscene. Look inside the boiler and pick up the Mirror Mask piece.