WE WERE HERE

‪This is a 2 player online only co-op game.
One player plays as the explorer and the other is the librarian
You need to do 2 and a half playthroughs to get all the achievements
The game takes about 15-20 mins to finish a playthrough
You have to playthrough once as the explorer then once as the librarian
Then you need to play up to the dungeon for the last achievement
You need to do each puzzle perfect the first time for an achievement
You also need to do a play through without dying
My video is 18 mins long and it will guide both sides through simultaneously
The explorer does most of the work

For this achievement you need to solve puzzle 7 (Theater) as the explorer. See in video at 11:15

Achievement Walkthrough:
Timestamps
Invite: 0:40
Puzzle 1 (Eyes): 1:30
Puzzle 2 (Paintings): 2:50
Puzzle 3 (Valves): 4:00
Puzzle 4 (Dungeon): 5:00
Puzzle 5 (Chess): 7:50
Puzzle 6 (Spikes): 9:25
Puzzle 7 (Theater) 11:15
Ending: 15:35‬

This is the last puzzle in the game. For this puzzle, we must explain what Scene to set up for our partner. They can use switches to bring out certain set pieces. After a scene is set up. They press the white switch to advance to the next scene.
Here is a guide for each scene:

Scene 1: Castle & People
Scene 2: Castle, King, & Queen
Scene 3: Castle, King, Queen, & People
Scene 4: Castle, Murdering King, Queen, and People
Scene 5: King Only, Activate "Blood Light"

After they need to press the white switch to confirm. This will unlock the hatch to the end of the game.
Here is my Video Guide: