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