Here is the full list of all 43 Tinykin achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Find all the artefacts stolen from Prattle's museum
Put back all the books on the messy shelves in Celerion
Go back to Aegis with Salvior Ardwin
Help Wolter organize the race in Celerion
Hatch a tinykin egg using another tinykin
Get the big wheel spinning in Celerion
Get behind the scenes in the house
Prepare Ardwin's Cake for Seross in Ambrose
Sneak into the pantry in Ambrose
Destroy 300 objects with explosive tinykin
Avoid drowning in extremis
Empty the sink in Ambrose
Break the biggest ice cube in Ambrose
Unlock the safe upstairs in Transidor
Break the damaged Matryoshka doll upstairs in Transidor
Fix the giant clock upstairs in Transidor
Mistreat the house's inhabitants 100 times
Get the party started in Balnea for Partipupa
Light up the dung beetles' lamp in Balnea
Survive a fatal fall in extremis
Liberate the funnel from Offrocker in Foliana
Reposition the nose on the fountain in Foliana
Light all the candles in a room
Let Ardwin's Canticle ring out across Sanctar
Give Sanctar's sphinx its nose back
Post every letter in a room
Help Sikaru prepare his first brew
Find one of the artefacts stolen from Prattle's museum
Rebuild the frog in Sanctar
Free the passage under the stairs in Transidor for Ridmi
Make friends with all the tinykin in the house
Help Sikaru with all his brews
Post every letter in the house
Light all the candles in the house
Be lunch for a carnivorous plant
Collect all the pollen in Transidor
Collect all the pollen in Sanctar
Collect all the pollen in Foliana
Collect all the pollen in Balnea
Collect all the pollen in Ambrose
Collect all the pollen in Celerion
Steal the pollen from the voracious plant in Transidor
Talk to Ghasper in each room