Here is the full list of all 32 Röki achievements.
Acquire all other badges
Find all of the petrified Trollbrothers
Say everything that needs to be said
Get to know the castle's inhabitants
Complete the game
Find all of the castle explorer's notes
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
Get to know the mill Tomte
Return Trollhilde's gold
Insult Shroomi
See beyond the veil
Awaken Jötunbjørn
Create a new path in the church
Examine 50 unique backpack items
Awaken Jötunúlfur
Have Fossegrim charm an instrument
Escape from the waterlogged caves
Open all of the Rootways
Activate the ice altar
Spin the top 5 times
Explore off the beaten track
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