Hardened Detective difficulty:
     Successfully  complete  the  game  under the Private Investigator
difficulty setting.

Mythos Master difficulty:
     Successfully  complete  the  game  under  the  Hardened Detective
difficulty setting.

"A" rank:
     Get  a 100% game completion to earn an "A" rank. This can be done
by  collecting all journal entries (thirteen in Jack's Diary, eighteen
in  General  Evidence,  and  six in Mythos Tomes), finding the rifle a
reception  office  door in the refinery, saving Ruth from the rafters,
and  keeping  enough  sailors  alive  during the boat ambush all under
three and a half hours with less than thirty saves done manually.

Variety Store: Safe combination:
     The combination to the safe in the Variety Store is 2-6-1-2.