Here is the full list of all 18 Simplz Zoo achievements.
Complete all 100 levels in the game
Purchase the Unicorn
Create a match that gives you at least 250 of any resource
Match 6 tokens at once
Match 7 tokens at once
Match 8 tokens at once
Match 9 tokens at once
Pass a level with under 10 seconds remaining
Pass a level with under 5 seconds remaining
Pass a level with under 2 seconds remaining
Raise your Zoo ranking into the Top 100
Raise your Zoo ranking into the Top 50
Raise your Zoo ranking into the Top 10
Increase your Zoo ranking to number 1
Purchase Mysterious Mansion
Purchase the Woolly Mammoth
Purchase the Yeti
Purchase the Saber-toothed Tiger