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