Here is the full list of all 35 Lovecraft's Untold Stories achievements.
Find every mini-event
Find 75% of the mini-events
See what was impossible to see
Find things not from this world
Defeat every Great Old One with the same character
Complete the story of any playable character without using the shops, and expelling them if you see one
Defeat Azathoth
Save the Earth from the Great Old Ones
Complete all the side quests
Collect 100% of the information of all the Great Old Ones
Complete the story of the Ghoul
Complete the stories of every playable character on HARD difficulty
Die in a strange place
Make every playable character go crazy, at least once
Defeat Nyarlathotep
Complete the story of the Thief
Collect 100% of the information of one of the Great Old Ones
Unlock the Ghoul
Defeat Shub-Niggurath
Complete the story of the Witch
Complete the story of any playable character without receiving any curse
Unlock the Thief
Defeat Cthulhu
Complete the story of the Professor
Get 5 curses of the Great Old Ones at the same time
Unlock the Witch
Eat 100 chocolate bars
Find a secret room without the Detective
Defeat Dagon
Complete any Great Old One location without having 100% information about it
Complete the story of one playable character on HARD difficulty
Unlock the Professor
Complete the story of the Detective
Spend 100,000 dollars and 100,000 information in the magazines
Make 1 playable character go crazy, at least once