Here is the full list of all 38 Cities: Skylines II achievements.
Unlock each building available in the base game.
Reach a population of 100,000.
Have 20 active transport lines. These can be passenger or cargo lines or any mix of the two.
Experience a hailstorm.
Experience a tornado.
Experience a forest fire.
Build any airport.
Unlock 150 map tiles in a single city.
Have 5 city policies active simultaneously.
Create 10 different districts in a single city and assign policies to each.
Follow a citizen's lifepath from childhood to old age.
Use the editor to make a map.
Reach milestone 20.
Experience all four seasons by building a city in a climate with a snowy winter.
Have 50 active transport lines. These can be passenger or cargo lines or any mix of the two.
Use the photo mode to take a screenshot.
Have at least 1000 citizens and an average happiness rating of 25%.
Use the editor to make an asset of any other type than map.
Have at least 1000 citizens and a city attractiveness rating of 90.
Build a city where at least 20% of the population has a university level of education.
Have a total loan of at least 200,000 in a single city.
Build 10 parks in a single city.
Bulldoze a total of 1000 buildings.
Have 6,000 citizens treated at medical clinics or hospitals in a single city.
Have a total of 10,000 tourist visits in a single city.
Build all unique city service buildings in a single city.
Build 10 signature buildings in a single city.
Build 5 signature buildings in a single city.
Unlock 50 map tiles in a single city.
Have a city that produces electricity by only using renewable energy sources.
Assign a policy to a city district.
Plant 100 trees or bushes with the landscaping tool in a single city.
Have a look at each individual info view panel.
Have at least 1000 citizens and an average happiness rating of 75%.
Create a city district and assign a city service to that district.
Reach enough milestones to unlock all city services in a single city.
Build city with residential, commercial and industrial zones, water, and electricity.
Have buildings from all four zone types in a single city.