Here is the full list of all 28 The Sinking City achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Leave the city and the world to their fate.
Restart the Cycle.
End the Cycle.
Defeat a little girl without playing fair.
Kill the priestess.
Kill the archeologist.
Have a ritual conducted on you.
Study all the frescoes in the Temple of Dagon.
Punish the upstart.
Challenge the horror of the Redemption Church.
Humor a grieving mother.
Help the professor with his plan.
Go below the surface for the first time.
Use the intelligence archives in your investigation.
Give an interview to the local newspaper.
Solve your first case in Oakmont.
Have your fortune read.
Press the button.
Betray the warehouse guard's trust.
Dethrone the patriarch.
Ask the Imperial Wizard to show you a magic trick.
Kill the old lady.
Finally commit the crime you were accused of.
Prevent the last self-immolation.
Agree to the experimental treatment.
Take Sidney's stash. You monster.
Uphold your agreement with Robert.
Complete every challenge Oakmont has to offer.