Here is the full list of all 13 PostCollapse achievements.
Survived 4 days in a single game
Survived 3 days in a single game
Survived 2 days in a single game
Survived 5 days in a single game
Survived 1 winter
Survived 2 winters in a single game
Survived 3 winters in a single game
Survived 4 winters in a single game
Killed a bear
Hunted 10 deers in a single game
Explored 8 cities in a single game
Successfully grew 20 plants in a single game
Caught 20 fish in a single game