Here is the full list of all 12 The Forgotten Ones achievements.
Got the FG-42.
Something is burning...
Beaten the game.
Schienzel is forever dead.
Got the meat cleaver.
You spared the tourists.
You killed the tourists.
Found the book of darkness.
Use an healthkit at low health.
You did what was necessary.
Got the SVT-40.
Discover the ritual room