Here is the full list of all 32 The Last Tree achievements.
Successfully complete Master Set Tundra
Successfully complete Master Set Grassland
Successfully complete Master Set Cave
Successfully complete Zone Z - Forest
Successfully complete Zone Y - Forest
Successfully complete Zone X - Forest
Successfully complete Zone W - Forest
Successfully complete Zone V - Forest
Successfully complete Zone U - Forest
Successfully complete Zone T - Cave
Successfully complete Zone S - Cave
Successfully complete Zone R - Cave
Successfully complete Zone Q - Cave
Successfully complete Zone P - Aquatic
Successfully complete Master Set Desert
Successfully complete Master Set Aquatic
Successfully complete Zone O - Aquatic
Successfully complete Zone N - Aquatic
Successfully complete Zone M - Aquatic
Successfully complete Zone L - Desert
Successfully complete Zone K - Desert
Successfully complete Zone J - Desert
Successfully complete Zone I - Desert
Successfully complete Zone H - Grassland
Successfully complete Zone G - Grassland
Successfully complete Zone F - Grassland
Successfully complete Zone E - Grassland
Successfully complete Zone D - Tundra
Successfully complete Zone C - Tundra
Successfully complete Zone B - Tundra
Successfully complete Zone A - Tundra
Successfully complete Master Set Forest