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