Here is the full list of all 10 Poly Towns achievements.
Accumulate 1,000,000 coins.
Accumulate 500,000 coins.
Have 1000 villagers.
Accumulate 100,000 coins.
Have 500 villagers.
Have 250 villagers.
Accumulate 50,000 coins.
Have 100 villagers.
Build your first town hall.
Accumulate 10,000 coins.