Here is the full list of all 15 Hidden Paws Mystery achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Find all cats and all yarns.
Find all the cats.
Find 100 yarns for all your cats.
Find a rabbit.
Reach the island with lots of rabbits.
Smash the pumpkins!
"Meow," the cat said, shy and hopeful.
Find 100 cats.
Find 50 yarns.
Find a penguin.
Reach the island of stone eyes.
Find 50 cats.
Find 25 cats.
Find 10 yarns.
Find 10 cats.