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 100 yarns for all your cats.
Find all the cats.
Reach the island with lots of rabbits.
Smash the pumpkins!
Find 50 yarns.
"Meow," the cat said, shy and hopeful.
Find 100 cats.
Find a penguin.
Reach the island of stone eyes.
Find 50 cats.
Find a rabbit.
Find 25 cats.
Find 10 yarns.
Find 10 cats.