Complete your first shelf.
Complete your first rack.
Unlock the first level of every upgrade path and unlock Double Jump.
Have 100 correctly sorted items at the same time.
Have 1,000 correctly sorted items at the same time.
Finish sorting all 4,060 items in one playthrough.
Max out every upgrade and unlock Double Jump.
Read the letter on the central table.
Open the cat's upgrade menu for the first time.
Open the hidden chest.