Here is the full list of all 16 100 Keys To Your Heart achievements.
Play as a key
Find the secret door
A secret in plain sight
Before you leave the castle...
Don't slip
Carefull with those spikes
Don't jump over it
Don't forget to check over the door
A clear lack of polish at the end, it's all glitchy
Reach the first padlock
Respawn 100 times
Switch keys 100 times
Enter the garden
Enterthe furnace
Enter the data area
Finish the game