After completing the game once, load up a save that hasn't seen the Piano scene with Mika and Nala yet and go into the outside area of the mansion, instead of heading left like normal go right and you will see a sparkle in an area near to a wall at the back. Normally you can't get it but after beating the game you can, it is the 'artifact' using it will generate a Hello.txt file in your folder, translate it using base64 converter for 4 phone numbers, the first 3 of them will lead you to locations where memory fragments can be collected, the final one when you have the 3 memory fragments, unlocks an option to walk away after unlocking the basement. Doing so triggers the Ending