Here is the full list of all 28 Mirror Forge achievements.
Complete the game.
Enter the Prison Dimension.
Find Jill.
Find the developer.
Reveal the forgotten truth.
Find the book about the Anunnaki in the Mirror Forge Facility.
Read the two papers in the Homeless Shelter.
Find the first Enlil's Tablet.
Uncover what happened to Jane.
Get to the countryside of Goreburg.
Find out who the dark entity is.
Escape the Woman Monster
Escape the Ashes Dimension.
Listen to the audio log in the Maintenance Room.
Find the Silent Hill Easter Egg
Poke the Eye
Escape the Invisible Monster in the hangar without taking a hit.
Experience the scare in the Hangar facility.
Show Mercy and fry the suffering Depression Monster.
See the massive beast in the Industrial Zone.
Make the acid in the Industrial Zone.
Use a Mirror to travel.
Get the Seal of Nur.
Find the 14 Frozen Moments.
Read the old tome in the Industrial Zone.
Find the changing painting in the Facility area.
Find Cageface in the Subway.
Inspect the Paper in the drawer in the Long Staircase area.