Here is the full list of all 39 Opus Castle achievements.
Drink until fall
Ending Dinner room
Interact with 7 verifiable items
Get a drink
Eat a little
Enter the dinner room
Find pin 1 of the key
Collect the cassette player
Final Suit
Collect the pot of mugwort
Steal the jewels
Collect 3 items
Open the drawers
See the photo of the suit
Enter the suite
Find pin 2 of the key
See the photo of the hall
Interact with 3 verifiable items
Check up the stairs
Interact with the mirror
Access the company's app
Change the cell phone's wallpaper
Use your cell phone flashlight
Find the base key
Play with the goat
Take a look around on the town
Try to run
Get run over
Enter Alvaro's bedroom
Go to the entrance
Find pin 3 of the key
Take a deep breath with the cigarette
Collect the invocation tape
Collect the Gun
See the photo of Alvaro's bedroom
See the pictures of the office
Ending Room of Álvaro
Final Office Room
Achieve all achievements