Note: Three of the Matryoasha dolls are found in Lucy's chapter, and are highly missable! The achievement "Matryoshka doll" is unlocked as part of this achievement.
To unlock this achievement, you must collect all ten Matryoshka dolls! To collect one, you need to click on it, and it will start to glow and disappear. Collected Matryoshka dolls can be found in the bookshelf near the grandfather clock on the upper floor.
Matryoshka dolls found in in the house
1. In the progress room, inside the white stand.
2. In the dining room cabinet, to the right when you come from the living room.
3. In the master bedroom, hidden in the lowest right drawer of the dresser by the bed end.
4. In the son's room, on the floor hidden behind some cardboard boxes and the large, wooden cabinet, behind the boxes.
5. In the garage attic, after moving the tool boxes and going into the hidden room with the Omega box, it sits on a cardboard box.
6. In the basement, inside the freezer.
7. In the unfinished corridors in the basement, hidden under and behind the wooden steps of a small set of stairs.
Matryoshka dolls found in Lucy's chapter
8. In the treehouse, under the small stand with the talking radio.
9. In a concrete room with tiny furniture, immediately after being locked in a room with a single birdcage containing a radio and a wooden bird, it will be on the floor by the wall and to the left of the furniture.
10. In the dark room with many large, wooden cabinets. From the door, go straight forward and you should bump into the side of one such cabinet. Go the right side doors of this cabinet, open it up, and there should be a bunch of white masks inside. Take a picture of them, and they will disappear, replaced by the Matryoshka doll.