Here is the full list of all 41 Ratopia achievements.
Place a citizen in a group.
Reach prosperity level 7
Reach 100 population
Keep at least 50 middle class for 12 days.
Upper class appeared in the city.
Order soldeirs to escort.
Destroy infected's grave.
Make trade agreement.
Build a decorative structure.
Experienced Winter's end.
Experienced Autumn's end.
Reach prosperity level 4
Middle class appeared in the city.
Find other cities.
Activate a shrine.
Experienced Summer's end.
Bury a dead to a grave.
Experienced Spring's end.
Rest on a Royal Bed
Activate a new policy.
Research a blueprint.
Assigne a ratizen to a job.
Accept a migrant.
Build a rail in the city.
Use a loan.
Build a huge monument.
Keep at least 50 upper class for 12 days.
Survive a year in Hard difficulty.
Saves 99,999 Pia.
Build Merchant Monument.
Build Noble Monument.
Produce an equipment
Change the style of the leader
Enter the dungeon
Destroy Weasel Barracks
Supply electricity to the city for the first time.
Assemble a Ratron at the Ratron Assembly Plant
Conquering the Forgotten Mine
Conquering the Barbaric Palace
Build Scientist Monument
Operate more than 30 Ratrons