I’m playing Signalis for the 6th time
Artifact ending (Secret ending)
KEY OF LOVE: Worker’s Quarter chapter, enter the Isolation room (top right room in the Northwest Corridor). The room has reddish light in it and four cages.
Set your receiver to 96.000 and turn your receiver on. With the receiver set, interact with the bottom portion of the lower right cage. You will have to interact with the cage for a few seconds (and get the message about the body being inside the cage) while the receiver plays, you’ll eventually get the prompt for taking the ==Key of Love==.
KEY OF ETERNITY: During the Protektors chapter, enter the STCR Dorm on the eighth floor (right bottom door in the Library Hallway). This room is dark and you’ll need the flashlight to explore it. Along the top side of the room (right side), find the small bookcase in between two beds. There are also two paintings on the walls on both sides of the bookcase. Set your receiver to 65.000 then interact with the bookcase a few times to find the ==Key of Eternity==.
KEY OF SACRIFICE: During the Rotfront chapter, after using the Itou code (560524) in the Backyard, you’ll enter the Backroom. While in the Backroom (where you can read the Song of Gods file), set your receiver to 240.000 and interact with the bookcase to the left of the “Song of Gods” file. Interact with the right side of that bookcase (corner near some stacked boxes) to receive the ==Key of Sacrifice==. The books on the shelf have some red stickers on them – once again, you have to face the shelf with the books then turn slightly toward the boxes to the right and then interact. WARNING - DO NOT pick up the Death card in the Book Store before getting this or your path to this key will be sealed off by pulsating flesh in the doorways.
Once all three keys are in your possession, wait until just before you solve the Moon cycle puzzle in the Atrium at the end of the Rotfront chapter. BE SURE to carry all three keys in your inventory on the way to the moon cycle puzzle. Solve the moon cycle puzzle and then you’ll be forced to move through the hole that appears below them. Once in the first person view room, turn to your right (nearly turning all the way around) then look down at the safe. Use all three keys on the safe to unlock the padlocks with chains on it. Enter the code “39486 60170 24326 01064” into the safe - this is the same code that Ariane gives over radio at the end of the prologue. Press the enter button then interact with the knob on the left side of the safe. Pick up the ==Flower== inside of the safe. The secret ending will play afterwards. No need to fight the final boss!