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