Here is the full list of all 40 The Forgotten City achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Topple 10 peeled statues by kicking others into them
Die from hornet stings
Free the captive and shoot her captor with your gun
Assemble as many people as possible in the Museum
Reach the best ending with the smallest number of loops
Talk your way through every possible confrontation
Allow Fabia to die in the collapsing temple
Read 10 different grafitti
Finish the game without looping through time once
Skip the city tour
Pick up the sponge on a stick
Reach Ending 1 of 4
Reach Ending 3 of 4
Lie 10 times
Reach Ending 4 of 4
Intimidate the creator of The Golden Rule
Loop through time ten times
Confront the creator of The Golden Rule
Have Duli released from his cell
Help Galerius romance Equitia
Solve Vergil's problem
Trigger The Golden Rule by stealing 5 times
Steal 2000 coins after the Golden Rule is broken
Use Photo Mode
Find all three missing persons
Dodge 3 boulders
Discover Underworld icons Sisyphus, Tantalus, Ixion and the Belide
Learn the true identity of the stranger by the river
Reach Ending 2 of 4
Save Ulpius's life
Enter the upper cistern in an unconventional way
Find treasure using the golden bow
Survive the Palace
Gild your first thing
Save Iulia's life
Save Fabia's life
Discover what lies beneath the city
Get rejected by Aurelia
Enter a villa with a daring leap
Loop through time once