In order to get this achievement, when you are in the Epilogue part, and once the last task has been revealed to you, head to the door on the floor just below the one at the top.














Once you enter the room, click on the dog that is sleeping in the foreground in front of you. You will then unlock the "Pet the dog" achievement.

At the menu of the game, just click on the "Please, Touch The Artwork 1" link and you will be redirected to the store page of the first game, unlocking the achievement.

Not really a missable achievement, but if you are struggling with remembering the sequence of the piano notes, it is the following:

• BCD
  
• BCDECA
  
• BCDECAEDC
  
• BCDECAEDCBCD
  
• BCDECAEDCBCDECAA

Thank you for reading this, it is my first try writing a guide, please let me know if I can improve it in any way!