Here is the full list of all 32 Röki achievements.
Acquire all other badges
Complete the game
Get to know the castle's inhabitants
Return Trollhilde's gold
Find all of the castle explorer's notes
Say everything that needs to be said
Open the gate to the tower
Solve the sundial puzzle
Solve the dining hall puzzle
Find all the Guardian banners in the castle
Complete Chapter 2
Insult Shroomi
See beyond the veil
Awaken Jötunúlfur
Find all of the petrified Trollbrothers
Have Fossegrim charm an instrument
Awaken Jötunbjørn
Examine 50 unique backpack items
Escape from the waterlogged caves
Open all of the Rootways
Create a new path in the church
Activate the ice altar
Get to know the mill Tomte
Summon a Tomte
Rescue the Great Mother Tree
Help a troll
Read every gravestone
Spin the top 5 times
Explore off the beaten track
Complete Chapter 1
Escort Lars to the outhouse
Successfully combine two items