1. Walk to the right to trigger the cutscene. (Press "Shift" to run.)
2. Go to the room on the far right and pick up the 'book'.
3. Open the door on the left side of the room, enter the study room, and take the 'key' from the bookshelf.
4. Exit the room, go to the room on the far left, turn on the light, pick up the 'note', and complete the puzzle to obtain the password "1974". Piecing it Together unlocked.
5. Open the door in the starting room, enter the bathroom, enter the code "1974" on the cabinet, and obtain the 'pills'.
6. Leave the bathroom and speak to any of the doctors in the room on the right.
7. Enter the study room, hold down "F" to use the medicine, and pick up the 'tape recorder'. Different Perspective unlocked.
8. In the new scene, open the door on the left to enter the room, then press "Space" to switch to the flashback
9. Enter the living room on the right and talk to the shadows.
10. Open the door inside the room, then enter the rooms in the order of 3-2-3 to pick up 'birthday present'.
11. Go back to the living room through the door on the right and talk to the shadows.
12. Walk to the kitchen on the right and pick up the 'kitchen knife' on the table.
13. After back to reality, return to the doctor’s room and talk to the doctor, then leave the room through the door on the right.
14. Enter the room on the right and have a conversation with the neighbor.
15. Hold down "F" to use the medicine, then pick up the 'key' on the wall.
*16. Enter the room on the far left, turn on the light, and pick up the 'cassette tape'.
*17. Go to the living room where the neighbor is, open the door on the left to enter the study room, hold down "F" to use the medicine, then enter the room on the left.
*18. Use the tape recorder on the cardboard box to obtain the piano music clue CABDEF.
19. Go back to the room with the piano. Play the piano in the order of CABDEF to obtain a 'fragment' of the research paper.
You can skip steps 16-18 and start playing the piano right away.
20. Open the door on the right side of the room, enter the bathroom, use the key on the cabinet, and obtain the second 'fragment'.
21. Enter the study room, complete the puzzle on the desk, walk to the right to trigger the cutscene, and leave the room.
22. Finish the conversation with the neighbor, then leave the room.
23. Knock on the door of Room 202, press "Shift" and running to the right until you unlock the final achievement On the Other Side.
