This is the walkthrough guide for the fourth and last ending: lost.
Check your bag and make sure you have both artifacts. One obtains from the Escape ending and another from the Release ending.
Enter portal and arrive at the top of the tower.
Follow our Imprisoned ending walkthrough guide to get a red beam, but do not enter the train.
Place the artifact with hexagon base on the left pedestal. Follow our Escape ending walkthrough guide to get a green beam.
Place the artifact with five-sided-shaped base on the right pedestal. Follow our Release ending walkthrough guide until you get the button on top of the artifact. Check out the front of the artifact. Locate a screw on the lens cover. Use the screwdriver to remove the screw. Slide the cover to reveal a smaller lens. Press the button.
Now you will have activate three beams: red, green, blue. All pointing at the door. The door will transformed into a liquid metallic surface. Enter the portal. You have complete the Lost ending and the game!