Here is the full list of all 13 Squirreltopia achievements.
Get 10,000 points total between all minigames
Win all 50 Time Trophies
Collect all 50 Gems
Collect All 15 Acorns
Unlock All Minigames
Defeat 5th boss and collect the factory key
Activate 1000 Bomb-Blocks
Defeat 4th boss and collect the alien key
Defeat 3rd boss and collect the desert key
Defeat 2nd boss and collect the ice key
Defeat 1st boss and collect the forest key
Waste 100 Squirrels
Collect an acorn