These achievements will lead you to the corresponding result:
Hardened Detective difficulty: Complete the game under the Private Investigator difficulty setting.
Mythos Master difficulty: Complete the game under the Hardened Detective difficulty setting.
"A" rank: Complete the game (100%).
Craig Mullins gallery: Complete the game under the Hardened Detective difficulty setting.
Background art renders: Complete the game under the Private Investigator difficulty setting.
Character art renders: Complete the game under the Private Investigator difficulty setting.
Concept artwork: Complete the game under the Private Investigator difficulty setting.
Variety Store Safe combination: The combination to the safe is 2-6-1-2.