One of the final tasks that can be done at the end of the game is to find a combination to open the final hatch. This hatch can be found in the ritual room and cannot be opened until the very end of the game.
Once you have managed to find a combination for this hatch you will then find the remains of Elizabeth Maxwell. We will also get a final end scene for having done this.
Okay let us begin.
As previously mentioned this section cannot be done until you are at the end of the game, when you will be attacked by Blue Knees.
After you are done dealing with Blue Knees we will now be limping around the area. So with this let us limp back to the ritual room.
Inside the ritual room we can then find the hatch that we need, it will be behind the chair. Now we need to find the combination to open it.
Thankfully we already have the combination that we need, we can find it by heading to the inventory and finding the collection of photographs.
In our photograph collection there will be several brown photographs with numbers on them. These numbers are what will be the necessary combination to the hatch. There should be a total of 4 brown photographs altogether.
Insert the combination from the photographs into the hatch, this will then unlock the hatch.
(Note: The combination to the hatch is random. So you will not be able to open this hatch without getting to the end of the game)
Here we will find the remains of Elizabeth Maxwell. Interact with the ashes to unlock a new vision, this should then result in the ashes being knocked off the plinth.
With the ashes now having been knocked off, go ahead and place your camera there instead. The chair behind you will have now moved.
Interact with the chair to unlock the ultimate final ending of the game.