Here is the full list of all 32 Röki achievements.
Acquire all other badges
Complete the game
Find all of the castle explorer's notes
Get to know the castle's inhabitants
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
Awaken Jötunbjørn
Have Fossegrim charm an instrument
Explore off the beaten track
Spin the top 5 times
Escape from the waterlogged caves
Examine 50 unique backpack items
Open all of the Rootways
Activate the ice altar
Return Trollhilde's gold
Create a new path in the church
Get to know the mill Tomte
Summon a Tomte
Rescue the Great Mother Tree
Help a troll
Read every gravestone
Complete Chapter 1
Escort Lars to the outhouse
Successfully combine two items